More than 600 mosquitos of the same species were caught in a single backyard trap in New South Wales over the weekend, proving the blood-sucking insects are thriving in wet weather.

Associate Professor Cameron Webb from NSW Health Pathology caught 605 "backyard mosquitoes", otherwise known as Aedes notoscriptus, in one Sydney trap on Sunday.

The species "readily attacks humans".

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Dr Webb told 9News.com.au the amount smashes the previous record of the same species caught.

"The previous highest amount of backyard mosquitoes caught was 417," he said.

"I'm trying to claim a new world record.

"(But) while this is a huge collection of this one particular species, it is only an 'average' collection for this time of year when considering all mosquitoes.

"Our biggest trap collection was over 35,000 mosquitoes in a single trap."

READ MORE: Monsoon 'burst' to explode over northern Australia

Last year Dr Webb predicted mosquito populations would explode due humid and wet weather conditions brought on by La Niña.

"This is absolutely what we'd expect to see given the conditions," he confirmed today.

"They're thriving because mosquitos prefer warmth, and they love water."

There are about 300 mosquito species in Australia and they're found in "most parts of Australia".

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Two mosquito-borne illnesses are found in Australia; Ross River virus and Dengue, which is found in the Top End.

While the risk is small, every state and territory in the country is potentially at risk of Ross River virus, Dr Webb added.

The best way to protect your flesh from mosquitoes is to wear a good insect repellent, which contains DEET, picaridin or lemon eucalyptus oil, Dr Webb said.

This should be re-applied after swimming or exercise.

Long sleeves, pants, shoes and socks should be worn wherever possible and outdoor plants and containers should be checked once a week to see if they've filled with water.

"Tip water-filled containers out, you don't want to provide a breeding ground for the insects," Dr Webb said.

As rain pounded the South Australian outback, a work trip quickly turned into an escape mission for Justin Hocevar and his colleagues.

They filmed as water from the continued downpour caused a large whirlpool next to the Stuart Highway near Pimba, 440km from Adelaide, and flash flooding trapped them.

"I've never seen anything like it before and we had similar feedback from a lot of the locals," Mr Hocevar told 9News.

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Mr Hocevar said his team got "rained in" with roads closed all around but eventually received an exemption to get people out because they were getting low on supplies.

It is believed that the worst of the state's summer storms has passed after a tropical weather system delivered a third day of heavy downpours, breaking apart roads and rainfall records.

Flash flooding left the Stuart Highway nearly submerged underwater, while in the state's far north record-breaking rain soaked parts of Kimba.

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Kadina on the Yorke Peninsula received the most rain that's ever fallen in 24 hours with 86.22mm.

The unseasonal three-day weather event started on Friday but the bureau says the cause, a tropical pressure system, isn't all that uncommon for this time of year.

"The tropical air masses is something that we do see reasonably often in summer, just not to this extent," the Bureau of Meteorology's Kylie Egan said.

A massive clean-up effort remains underway.

"We want to get behind and support those communities who are most impacted both from an infrastructure perspective and we're also hearing about some soil erosion," Premier Steven Marshall said.

The Pentagon said up to 8500 US troops have been put on heightened alert for a possible deployment to Eastern Europe as Russian troops mass on Ukraine's border.

US Secretary of Defence Lloyd Austin issued the prepare-to-deploy orders at the direction of President Joe Biden.

Pentagon spokesman John Kirby said on Monday (US eastern time) no final decision to deploy the troops had been made.

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The Biden administration was in in the final stages of identifying specific military units it wants to send to Eastern Europe, according to multiple US and defence officials.

"What this is about is reassurance to our NATO allies," Kirby said.

Meanwhile, British Prime Minister Boris Johnson has warned Russia that invading Ukraine would be a "painful, violent and bloody business".

Mr Johnson said the situation was "pretty gloomy" but war was not inevitable, the BBC reports.

https://twitter.com/DeptofDefense/status/1485701744281673731?ref_src=twsrc%5Etfw

He said the Kremlin was preparing for a "lightning war".

"The intelligence is very clear that there are 60 Russian battle groups on the borders of Ukraine, the plan for a lightning war that could take out Kyiv is one that everybody can see," Mr Johnson said.

"We need to make it very clear to the Kremlin, to Russia, that that would be a disastrous step."

Putin seeking 'invasion trigger'

International security expert John Blaxland told Today this morning that Russian President Vladimir Putin is seeking an excuse to invade Ukraine and install a pro-Kremlin regime.

"Putin is looking for an excuse to trigger what he wants to do which is to overthrow the regime in Ukraine and establish a state that is compliant and compliant with what he wants," Professor Blaxland, of the Australian National University Strategic and Defence Studies Centre, said.

He also warned that unless moderate Kremlin figures pulled Mr Putin back from increasing tensions, conflict was likely.

"If he's not prepared to back down or if his backers in Moscow don't rein him in, that's hard to see anything other than a conflict emerging. That's what we call a war."

Professor Blaxland said Australia would have to be cautious about offering military aid for Ukraine.

"We have already talked about some intelligence support and particularly on the cyber security front and I think that's where we have a bit of expertise," he said.

Australians urged to leave Ukraine

Australians have been urged to leave Ukraine as soon as possible amid growing concerns of a potential Russian invasion.

The Australian Government updated its travel advice on Monday night and also directed dependants of embassy staff in Kyiv to leave, "reflecting the increased risk of armed conflict".

The direction came after NATO announced it was putting extra forces on standby and sending more ships and fighter jets to eastern Europe amid Russia's troop build-up near Ukraine.

READ MORE: NATO sends ships, fighter jets to eastern Europe

https://twitter.com/Smartraveller/status/1485576204006887426

"Australians in Ukraine should leave now by commercial means, where safe to do so, noting that flight availability could change or be suspended at short notice," a Department of Foreign Affairs and Trade spokesperson said.

"Security conditions can change at short notice. Consular services and our ability to provide consular assistance to Australians may be limited due to local circumstances.

"Australians who decide to remain in Ukraine should review their personal security plans, be prepared to shelter in place if required, maintain heightened security awareness and register with DFAT.

There is currently no indication the government is planning repatriation flights for Australians to leave Ukraine.

Other countries have taken similar measures, including reducing the number of staff at their embassies.

DFAT has created a portal for Australian citizens in Ukraine to register their whereabouts.

People are being told to monitor local media and Australian government channels for updated security advice, and have a plan in place for if the situation changes.

"Make sure your visas and passports are up to date, including for your immediate family," the warning says on the SmartTraveller website.

"If your departure plan involves a vehicle, make sure registration, ownership, insurance and Green Card is in order for border crossings. Carry identification with you at all times and communicate with family and friends about your travel plans."

DFAT warns consular services and the ability to provide consular assistance could become limited.

NATO allies sending boats, jets to eastern Europe

Amid widespread Western concerns over Russia's massing of troops near the Ukraine border, NATO said it was beefing up its "deterrence" presence in the Baltic Sea area.

Denmark is sending a frigate and deploying F-16 war planes to Lithuania; Spain will also send warships and could send fighter jets to Bulgaria; and France stands ready to send troops to Bulgaria.

"I welcome allies contributing additional forces to NATO," NATO Secretary General Jens Stoltenberg said.

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https://twitter.com/MarisePayne/status/1485081367549743105

"NATO will continue to take all necessary measures to protect and defend all Allies, including by reinforcing the eastern part of the Alliance.

"We will always respond to any deterioration of our security environment, including through strengthening our collective defence.

– Reported with CNN, Associated Press

A monsoon trough is deepening over northern Australia and is expected to explode, bringing heavy rain and "gusty" thunderstorms to two states and a territory.

The main threats as of the monsoon "burst" will be heavy rain, flooding, lightning and damaging winds.

Weatherzone warns Queensland, Northern Territory and Western Australia are in the firing line.

READ MORE: Aussies warned to leave Ukraine as invasions fears grow

The system is expected to bring heavy rainfall "up to several hundred millimetres" in some places, as well as "frequent gusty thunderstorms".

"While tropical cyclones look unlikely this week, the lows and monsoon trough will still enhance rainfall and bring severe storms to a broad area of northern Australia, extending from the Kimberley, across the northern NT and into eastern tropical QLD," Weatherzone wrote.

"Large rainfall totals (are) expected across northern Australia. Active periods of the monsoon like this typically cause widespread weekly rainfall totals of more than 100 millimeters, with some places likely to see several hundred millimeters by the end of this week."

It comes after South Australia was hit with heavy downpours for a third day.

Flash flooding left the Stuart Highway nearly submerged underwater, while in the state's far north record-breaking rain-soaked parts of Kimba at the top of Eyre Peninsula.

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Kadina on the Yorke Peninsula received 86.22mm in 24 hours.

It's believed the worst of the summer storms are now over but a number of roads remain closed as repair work is carried out.

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https://twitter.com/DFIT_SA/status/1485435188037718016

Read on to find out what conditions will be like across the nation's capitals.

Brisbane

The mercury will climb to 31C in Brisbane, which has a cloudy day in store.

There's a medium chance of showers, most likely during this afternoon and evening.

Sydney

Sydneysiders have woken to a cloudy, overcast day. However there is only a slight chance of a shower.

The temperature will climb to 27C.

Melbourne

It will be a humid and hot day in Melbourne, with temperatures forecast to reach 32C.

It will be partly cloudy.

There's also a chance of a late afternoon shower or thunderstorm in the outer northeastern suburbs.

Canberra

The nation's capital will reach a high of 29C today.

It will be partly cloudy, with a slight chance of a shower. An afternoon or evening thunderstorm is also possible.

Hobart

It will be partly cloudy in Hobart as temperatures reach 24C.

The BoM said there's a slight chance of a shower later tonight.

Light winds will become southeasterly 25 to 40 km/h in the middle of the day.

Adelaide

Adelaide is in for another humid day with temperatures expected to hit 29C.

There's a medium chance of showers, most likely from late this morning.

Darwin

The mercury will hit 31C in Darwin.

There's also a high chance of showers, and a possible thunderstorm.

Perth

It will be a clear day in Perth, with temperatures in the city expected to reach 31C.

Winds will tend south to southeasterly at 25 to 35 km/h.

WikiLeaks founder Julian Assange has won the first stage of his effort to overturn a UK ruling that opened the door for his extradition to the United States to stand trial on espionage charges.

The High Court in London gave Assange permission to appeal the case to the UK Supreme Court. But the Supreme Court must agree to accept the case before it can move forward.

"Make no mistake, we won today in court," Assange's fiancee, Stella Moris, said outside the courthouse, noting that he remains in custody at Belmarsh Prison in London.

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"We will fight this until Julian is free," she added.

The Supreme Court normally takes about eight sitting weeks after an application is submitted to decide whether to accept an appeal, the court says on its website.

The decision is the latest step in Assange's long battle to avoid being sent to the United States to face espionage charges over WikiLeaks' publication of classified documents more than a decade ago.

Just over a year ago, a district court judge in London rejected a US extradition request on the grounds Assange was likely to kill himself if held under harsh US prison conditions.

US authorities later provided assurances that the WikiLeaks founder would not face the severely restrictive conditions that his lawyers said would put his physical and mental health at risk.

READ MORE: Aboriginal flag 'freed' for public use in $20 million Federal Government copyright deal

Last month, the High Court overturned the lower court's decision. High Court justices Ian Burnett and Timothy Holroyd said the American promises were enough to guarantee Assange would be treated humanely.

They said the US promises were "solemn undertakings, offered by one government to another, which will bind all officials and prosecutors who will deal with the relevant aspects of Assange's case now and in the future."

Assange's lawyers said those promises can't be trusted, and have sought permission to appeal to Britain's highest court.

They argued the US government's pledge Assange wouldn't be subjected to extreme conditions was meaningless because it was conditional and could be changed at the discretion of American authorities.

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Nick Vamos, a partner at Peters and Peters solicitors in London and a former head of extradition at Britain's Crown Prosecution Service, had said it was unlikely the appeal would be granted.

Assange, 50, has been held at the high-security Belmarsh Prison in London since 2019, when he was arrested for skipping bail during a separate legal battle.

Before that, he spent seven years holed up inside Ecuador's Embassy in London.

Assange sought protection in the embassy in 2012 to avoid extradition to Sweden to face allegations of rape and sexual assault.

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Sweden dropped the sex crimes investigations in November 2019 because so much time had elapsed.

American prosecutors say Assange unlawfully helped US Army intelligence analyst Chelsea Manning steal classified diplomatic cables and military files that WikiLeaks later published, putting lives at risk.

Lawyers for Assange argue their client shouldn't have been charged because he was acting as a journalist and is protected by the First Amendment of the US Constitution that guarantees freedom of the press.

They say the documents he published exposed US military wrongdoing in Iraq and Afghanistan.

If you or anyone you know needs immediate support, contact Lifeline on 13 11 14 or via lifeline.org.au. In an emergency, call 000.

The Aboriginal flag can now be freely used like the national flag after the Federal Government bought the copyright in a historic deal with the emblem's creator.

The $20.05 million deal ends ongoing controversies over the flag's use stemming from non-Indigenous company WAM Clothing buying the exclusive rights to the flag in November 2018.

The licence had meant anyone wishing to use the flag on clothing or in physical and digital media had to ask permission and pay a fee. Several organisations were sent cease-and-desist notices.

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But with the transferral of the copyright to the Commonwealth, Prime Minister Scott Morrison said the flag had been "freed" for all Australians, allowing it to be used "in a similar manner to the Australian National Flag".

That includes use on sporting jerseys and grounds, websites, paintings and other artworks, without asking for permission or paying someone.

The AFL in 2020 notably refused to pay the licenceholder to fly the flag or paint it in the centre circle, in support of the growing Free the Flag campaign by Spark Health's Clothing the Gap.

The flag's creator, Luritja artist Harold Thomas, said he hoped the arrangement would provide comfort to Aboriginal people and other Australians to use the flag "unaltered, proudly and without restriction".

"I am grateful that my art is appreciated by so many, and that it has come to represent something so powerful to so many," he said, in a government statement announcing the purchase.

"The Aboriginal flag design is my dreaming, intertwined with my wife's family and mine, our ancestral belonging. The land, and the landscape, is indelible in my make-up; it courses through my consciousness and subconsciousness.

"The flag represents the timeless history of our land and our people's time on it. It is an introspection and appreciation of who we are. It draws from the history of our ancestors, our land, and our identity and will honour these well into the future."

Indigenous Australians Minister Ken Wyatt said the flag was an enduring symbol close to the heart of the Aboriginal people but securing the copyright was important for all Australians.

"Now that the Commonwealth holds the copyright, it belongs to everyone, and no one can take it away," he said, in a statement.

The flag incorporates three elements — red land, Black people and yellow sun — and its "simplicity is the strength of it", according to its creator.

It was made to lead a demonstration in Adelaide in 1971 on National Aborigines Day, the forerunner of NAIDOC (National Aboriginal and Islander Day Observance Committee) Week, but had its roots in the march from the year before.

"There was a gathering of Aboriginals around Australia in capital cities to stand up and to be counted," Thomas said, describing the flag as a symbol of unity and pride.

"I said 'I'm proud I'm Aboriginal, I'm proud I'm Black and I got something to be grateful for about our heritage and our culture'.

"So that's possibly the centre and the reason why the Aboriginal flag came into being."

NAIDOC welcomed the announcement, on Twitter, as did Labor MP for Cooper Ged Kearney and AFL executive general manager of inclusion and social policy Tany Hosch.

Northern Territory Labor Senator and Senate Select Committee on the Aboriginal Flag chair Malarndirri McCarthy said she would be examining the deal in Senate estimates, "in particular the copyright and custodianship of the flag".

"I'd like to commend the people (who) advocated to help resolve this," she said.

Thomas retains moral rights over the flag but its use will no longer be restricted by WAM Clothing or any other company. 

"I still own the elements of it, the integrity of it, that it's my design," he said. 

"And it comes from my household, which is an Aboriginal family household. 

"And it's important to say this, the Aboriginal family household are the fundamental keepers of the culture of the Aboriginal people."

A spokesperson for the Indigenous Australians Minister's office said the total cost included a payment to Thomas for the copyright and "payments to the licensees for termination of their licences".

According to the government, Thomas has indicated he'll use $2 million to establish an Australian Aboriginal Flag Legacy not-for-profit.

The artist will give an original painting to the Commonwealth for initial display at Parliament House and says he plans to hold onto a non-fungible token (NFT) of the flag, minted on December 21, on behalf of Indigenous communities.

The government said Carroll and Richardson Flagworld would remain the "exclusive licensed manufacturer and provider" of Aboriginal Flags and buntings but any future royalties received by the Commonwealth would go towards NAIDOC.

The World Health Organisation's director-general has warned that conditions remain ideal for more coronavirus variants to emerge and it's dangerous to assume Omicron is the last one or that "we are in the endgame".

But Tedros Adhanom Ghebreyesus said the acute phase of the COVID-19 pandemic could still end this year if some key targets are met.

Dr Tedros has laid out an array of achievements and concerns in global health over issues like reducing tobacco use, fighting resistance to anti-microbial treatments, and risks of climate change on human health.

But he said "ending the acute phase of the pandemic must remain our collective priority".

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"There are different scenarios for how the pandemic could play out and how the acute phase could end. But it's dangerous to assume that Omicron will be the last variant or that we are in the endgame," Dr Tedros told the start of a WHO executive board meeting this week.

"On the contrary, globally, the conditions are ideal for more variants to emerge."

But he insisted that "we can end COVID-19 as a global health emergency, and we can do it this year," by reaching goals like WHO's target to vaccinate 70 per cent of the population of each country by the middle of this year, with a focus on people who are at the highest risk of COVID-19, and improving testing and sequencing rates to track the virus and its emerging variants more closely.

Omicron is less likely to cause severe illness than the previous Delta variant, according to studies.

Omicron spreads even more easily than other coronavirus strains, and has already become dominant in many countries.

It also more easily infects those who have been vaccinated or had previously been infected by prior versions of the virus.

"It's true that we will be living with COVID for the foreseeable future and that we will need to learn to manage it through a sustained and integrated system for acute respiratory diseases" to help prepare for future pandemics, Dr Tedros said.

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"But learning to live with COVID cannot mean that we give this virus a free ride. It cannot mean that we accept almost 50,000 deaths a week from a preventable and treatable disease."

In stark terms, Dr Tedros also appealed for strengthening WHO and increasing funding for it to help stave off health crises.

"Let me put it plainly: If the current funding model continues, WHO is being set up to fail," he said.

"The paradigm shift in world health that is needed now must be matched by a paradigm shift in funding the world's health organisation."

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The head of WHO's European region, Hans Kluge, said separately in a statement that Omicron "offers plausible hope for stabilisation and normalisation," but cautioned: "Our work is not done."

He was alluding to signs that the new variant has shown to bring with it less severe disease, even if it's more transmissible.