Police say a body believed to be that of missing TV presenter Michael Mosley has been found on a Greek island.

A police spokesman, who spoke on condition of anonymity today (tonight AEST) because of an ongoing investigation, said the body was found on a rocky coast by a private boat and that formal identification was pending.

The British television presenter disappeared while on holiday on the island of Symi, which is on the eastern side of the Aegean Sea and about 6.5 kilometres from Turkey.

READ MORE: Why is Australia so successful at the Olympics?

A search and rescue operation has been under way since Wednesday.

Mosley, 67, is believed to have gone for a coastal walk along Saint Nicholas Beach on Wednesday afternoon while on holiday on the island, which is a popular destination for hikers.

Mosley is well-known in Britain for his regular appearances on television and radio and for his column in the Daily Mail newspaper.

He is known outside the UK for his 2013 book The Fast Diet, which he co-authored with journalist Mimi Spencer.

The "5:2 diet" set out how people can lose weight fast by minimising their calorie intake for two days in a week while eating healthily on the other five.

Rescuers were earlier focusing their search efforts on a maze of tunnels known as 'The Abyss'.

READ MORE: Man hands himself in to police after alleged fatal hit-run in Melbourne

At least 100 rescuers and volunteers, including a helicopter, were scouring the area between Agios Nikolaos and the island's main town in search of the 67-year-old.

In a statement yesterday, Mosley's wife Clare said the days in which her husband went missing were "the longest and most unbearable".

"The search is ongoing and our family are so incredibly grateful to the people of Symi, the Greek authorities and the British consulate who are working tirelessly to help find Michael," she said.

The couple's four children were on their way to the island to aid in the search. 

He later introduced the Fast 800 diet, a rapid weight loss program, and has made a number of films about diet and exercise.

Mosley often pushed his body to extreme lengths to see the effects of his diets.

He lived with tapeworms in his guts for six weeks for the BBC documentary Infested! Living With Parasites.

– Reported with Associated Press 

‘We believe these injuries were not accidental.’

Act’s polling suggests it could drastically improve its 2023 party vote.

The viewing had changed from an open home to a kerbside gathering of potential buyers.

Nine Entertainment Co chairman and former federal treasurer Peter Costello has resigned from his role and stepped down from the company's board.

Costello, who was appointed in 2016, will be succeed by current deputy chair Catherine West, who has worked in the media and entertainment industry for over 30 years in the United Kingdom, Europe and Australia.

In an email to all staff on Sunday afternoon, Nine CEO Mike Sneesby said the board wished to thank Costello for his contribution to Nine over more than a decade, including eight years as chairman.

"Mr Costello played a key role in Nine milestones such as its successful re-listing on the Australian Stock Exchange in 2013, securing the landmark news media bargaining code and the transformative merger with Fairfax Media," Sneesby said.

"I want to thank Peter for his contribution to Nine over more than a decade.

"As the announcement makes clear, he has played an important role in the big Nine milestones over that time – a period marked by dramatic digital transformation for the media industry and our company.

"Our deputy chair Catherine West has been appointed as chair and will lead existing plans for board renewal.

"It has been a challenging few weeks for our company and I want to express my heartfelt appreciation to all of you for your hard work."

Costello thanked the board for their support over the last decade and particularly during the events of the last few weeks.

"After nearly eleven years on the board of Nine Entertainment Company (NEC) and more than eight years as chair, I had flagged retiring from the board some time after the July Olympics and by the AGM in November at latest," wrote Costello.

"Last year, the company retained a search firm to identify new directors. The work is well advanced.

"I have today informed the board of NEC that I will pull forward that timing, stand down as chair and resign as a director.

"The deputy chair Catherine West has been working with the search firm and is well placed to chair the company and conclude the process of refreshing the board.

"The board has been supportive through the events of the last month and last few days in particular. But going forward I think they need a new chair to unite them around a fresh vision and someone with the energy to lead to that vision for the next decade."

West added: "On behalf of the board I want to thank Peter for his dedication and commitment to Nine.

"Peter has led the transformation of Nine from a free-to-air network to a fully integrated media company with traditional and digital media assets across television, streaming publishing, audio and marketplaces.

"As chairman, he has always put the needs of the company first and his decision to stand down and pass on the baton of leading Nine at this time is in line with that approach."

Costello was treasurer of the Commonwealth of Australia from March 1996 to December 2007, and was the longest serving treasurer in Australia's history.

Last week Costello denied assaulting a journalist who was asking him questions in Canberra Airport about Nine's handling of allegations following the departure of TV news boss Darren Wick.

Nine is the publisher of this website.

Family putting hope in CAR T-cell therapy, but need funds to get them to Melbourne.

She said there was a direct link between her alcohol addiction and her autism and ADHD.

The jackpot has been split between seven lucky players, who each picked up $7 million.

The woman feared a harmful person from her past could have accessed her information.

Inquiries into the incident remain ongoing.