Victoria's new coronavirus outbreak grows to 10

Cars have queued for up to five hours awaiting a coronavirus test in Melbourne today, with no guarantee of reaching the front as the number of cases grew.

Several south eastern testing stations were forced to close early, with dedicated frontline staff simply unable to meet the demand of people urgently seeking a COVID test.

Late today the Health Department confirmed another two COVID cases have emerged in Victoria with clear links to existing infections that were seeded at the Smiling Buffalo Thai Restaurant earlier this week.

The two new positive cases dined at the restaurant on December 21 before travelling into southern NSW where they learned of the outbreak and got tested before returning home.

Because the new infections were identified in NSW they will only be officially added to Victoria's tally on Saturday, bringing it to 10.

Authorities are yet to pin down who started the outbreak.

"Until we identify the absolute index case and its connections to every other case, of course we remain concerned," COVID Testing Commander Jeroen Weimar said.

Health Minister Martin Foley is almost convinced it came from interstate.

"The NSW link is still our primary line of investigation for this outbreak," he said.

"We expect genomic testing to come through very shortly and to assist us in confirming the lines of enquiry for our investigation."

More than 170 close contacts and positive cases are in self-isolation, spread across several suburbs and beyond Melbourne into Leongatha and Barwon Heads.

"This is not just a Bayside issue, this is a wider Victorian exposure risk," Mr Weimar said.

There were 13,108 test results received yesterday.

Face masks have become compulsory (except in your own home), house guests have been cut from 30 to 15 souring last night's New Year celebrations.

Border shuts

There have been long queues at the border as thousands race home from NSW before they're locked out at midnight. From tomorrow, any returning Victorian will need to be tested and also self-quarantine for 14 days.

"I stood here some time ago and reconsider going to NSW, don't go to Sydney," Mr Foley said.

"Reconsider going to NSW because the border can change quickly on the basis of public health advice and we saw that happen yesterday. Today, I say, if you are returning to Victoria as of today you must get tested and you must isolate for 14 days."

Mr Weimar warned returned travellers about further lengthy queues at the Victorian border.

"The border to NSW will shut at 11.59pm tonight. Anybody who is at queue at the border at 11.59pm will be allowed to go through but that does not extend to people wandering through at 8am tomorrow morning," Mr Weimar told reporters.

"So please, if you are in NSW and you want to be back in Victoria you need to leave now if you haven't left already.

"You need to prepare for a lengthy wait at the border. So please ensure you have fuel, water, food and also whatever you need to isolate safely when you get home."

He said warnings about the risks of getting stranded "on the wrong side of the border" have been issued for days so travellers must decide where they intend to stay.

"If that's NSW that's absolutely fine, if you intend to return to your home in Victoria you need to be getting on the road now," he said.

Victoria's Acting Premier Jacinta Allan said it was a difficult but necessary decision.

"We have to do everything we possibly can to lock in the situation we have here in Victoria, keep ahead of where case numbers might be, especially in light of case numbers coming out of NSW and to protect the precious gains we have achieved over the course of 2020 here in Victoria," she said.

The latest directions in Victoria come as NSW recorded 10 new cases yesterday, with five linked to the Avalon cluster.