CCTV has emerged in the disappearance of celebrity doctor Michael Mosley, which appears to show him in a town less than half an hour after leaving his wife at a beach on a Greek holiday island.

The footage shows a man wearing the same blue clothes, cap and sunglasses as 67-year-old Mosley, and shouldering an umbrella, in the village of Pedi, on the Greek island of Symi.

The CCTV was captured about 20 minutes after Mosley left the secluded Agios Nikolaos (St Nikolas) beach to walk back to the port town where he and his wife were staying.

Stills released by Greek police show the healthy living guru in the main street of Pedi, which is about one quarter of the way through the return walk to Symi town.

Mosley, a father of four, set out alone on the short stroll on a rocky coastal path in searing heat on Wednesday (local time).

CCTV shows a man dressed the same as Dr Michael Mosley about 20 minutes after he left the beach. Photo: Supplied

The doctor, known for endorsing fasting diets, was last seen at 1.30pm when he told his wife Dr Claire Bailey and their friends he was walking back where they were staying.

The CCTV footage was captured in Pedi’s main street roughly 20 minutes later.

The BBC reports that officials are now understood to be excluding the possibility that Mosley came to harm while walking between the beach and Pedi on an easy-to-navigage path.

The extensive search and rescue operation involving drones had previously been focussing on the path between Agios Nikolaos beach and Pedi.

Police, the fire brigade, coast guard and volunteers were searching for Mosley on land and sea, using a helicopter, drones and a rescue dog as temperatures hit 40C.

The path between Agios Nikolaos beach and the port of Pedi skirts the coastline. Photo: Getty

Symi Mayor Lefteris Papakalodoukas told the ABC that authorities had “eliminated” the theory that Mosley vanished between the beach and Pedi.

However, from Pedi to Symi there were no more cameras to shed further light on his movement, he said.

Mosley did not have his mobile phone with him, which made tracing him more difficult.

“So far, we don’t have evidence of what may have happened, whether it is an accident … or something else,” said a senior police official who declined to be named.

Police were looking into reports he had spoken to locals halfway through his walk.

The mayor said it was a 10-minute walk from the beach to Pedi. It would take another 40 minutes to reach a main road.

“It is very strange,” Papakalodoukas told reporters. “You can’t disappear, you can’t get lost.”

A photo of Michael Mosley that was released in a public appeal. Photo: Facebook

The Daily Mail reports that Mosley and his wife landed on the 16km-long island on Tuesday (local time) and were due to stay for a week with a couple who have a house in Symi Town.

The two couples took a boat-taxi from Symi Port on Wednesday morning, stopping at Agio Nikolaos beach where Mosley swam in the sea before deciding to walk back home.

Symi is a sparsely populated rocky island in the eastern Aegean. It is about 16km long with around 2500 residents.

CCTV footage in the town of Pedi shows a man with an umbrella. Photo: Supplied

Mosley, 67, is well known in Britain for programs including the BBC series Trust Me, I’m a Doctor. He has also appeared on the BBC’s The One Show and ITV’s This Morning.

He popularised the 5:2 diet, which endorses intermittent fasting.

There were dozens of expressions of concern among colleagues and friends on social media for Mosley and his wife and family.

The story was on the front page of the Daily Mail newspaper, where Mosley is a columnist.

Dr Michael Mosley has gone missing on a Greek island. Photo: AAP

-with AAP