• Dr Mosley was reported to have left Agios Nikolaos beach by foot on Wednesday at 13:30 local time (11:30 BST).
• A search and rescue operation, involving helicopters and drones, has started up again on Saturday morning.
Image: Facebook
The search for missing TV and radio presenter Michael Mosley has shifted to a remote mountainous area on the Greek island of Symi.
The 67-year-old, known for his TV programmes and BBC Radio 4's Just One Thing podcast, vanished on Wednesday while on holiday.
Dr Mosley was reported to have left Agios Nikolaos beach by foot on Wednesday at 13:30 local time (11:30 BST), and new CCTV footage seen by PA news agency shows him later entering a mountainous path inland from a nearby village.
A search and rescue operation, involving helicopters and drones, has started up again on Saturday morning.
At 06:00 local time firefighters started searching a 4 mile (6.5km) radius over a mountainous area that is surrounded by sea, said Manolis Tsimpoukas who organises searches for missing people on the Dodecanese Islands, of which Symi is apart of.
Asked if there had been any sign of Dr Mosley, he said there has been "nothing".
A source directly involved in the search told BBC News the search is focusing on the mountainous area between areas of the island Pedi and Symi. The source described it as "not easy terrain".
One theory that has emerged was that Dr Mosley was trying to take a much longer route than previously thought, passing over miles of exposed hillside. Dr Mosley's accommodation was in the main town.
CCTV images appear to capture the broadcaster in Pedi’s main street holding an umbrella about 20 minutes after leaving the beach.
The BBC has seen a second piece of CCTV footage from a nearby premises showing a man wearing the same clothes and carrying the same umbrella which was time stamped at 13:50.
Officials are now understood to be excluding the possibility the father-of-four came to harm while walking between the beach and Pedi.
Separate CCTV, from a house at the edge of Pedi’s marina at the far end of the village, shows Dr Mosley later entering a mountain path at about 14:00 local time, PA said.
A member of the rescue team described the search as a “race against time” and said he could be “anywhere”.
"The path is not easy to follow, if he took a wrong turn, he would be lost,” she told PA.
His four children have arrived on Symi to help with the search. His wife Dr Clare Bailey Mosley has also been searching the island joined by her British friends, Symi's mayor said.
All patrol boats, private boats and commercial boats near the island have been searching for Dr Mosley, Symi’s coastguard said, while police and firefighters have been using drones and a sniffer dog to try to locate the missing presenter,
Divers have been "looking into the water" with the help of the Hellenic Coast Guard.
Symi's mayor Eleftherios Papakaloudoukas said the search will continue until Dr Mosley is found.
He added he was unsure why the missing presenter would try to make a long, potentially arduous journey in such heat, but he hoped the presenter is found "safe and alive".
Greek police said Dr Mosley left his wife on the beach on Wednesday, before setting off on a walk to the centre of the island.
His phone was found where he was staying with his wife, who reported him missing, a police spokesperson told BBC News.
An appeal saying he was missing was posted on a local Facebook group on Wednesday, alongside a picture of Dr Mosley wearing a blue cap, polo shirt and shorts.
"Have you seen this man? He set off to walk back from [Agios Nikolaos beach] at about 13:30 and failed to make it home," it said.
Symi is part of Greece's Dodecanese island group and sits about 12 miles (19km) north-west of Rhodes. In the 2021 census it had a population of approximately 2,600 people.
The majority of its beaches are remote and people are advised to take boats to visit them.
Father and daughter Antonis and Maria, who have lived on Symi all their lives, said his disappearance is shocking and confusing.
“This is crazy,” Antonis told BBC News.
“The place is very small. A little kid can’t get lost here. How does a man get lost?”
Before moving into TV, Dr Mosley studied medicine in London and qualified as a doctor but for the last couple of decades has been working as a presenter, documentary maker, journalist and author.
He writes a column for the Daily Mail and his TV programmes also include Channel 4 show Michael Mosley: Who Made Britain Fat?
Dr Mosley has been an advocate for intermittent fasting diets, including the 5:2 diet and The Fast 800 diet.
His wife Clare Bailey Mosley, is also a doctor, author and healthy living advocate.
The couple recently appeared at the Hay Festival where Dr Mosley presented a special edition of Just One Thing.
Reacting to the "shocking news", his fellow Trust Me, I'm A Doctor co-star Dr Saleyha Ahsan said she was "praying he is found safe" and she feels "sick with worry".
On Thursday's edition of The One Show, presenter Alex Jones opened the programme by expressing concern that "our friend" had gone missing.
"Our thoughts are very much with his wife Clare and the rest of his family at this worrying time. We hope for more positive news," she added.
Timeline
Wednesday 1330 local time (11:30 BST) - Dr Michael Mosley leaves his wife Clare on Agios Nikolaos beach and sets off on a walk
1350 - He is seen on CCTV in Pedi
About 1400 - CCTV footage seen by PA news agency shows Dr Mosley at the edge of Pedi’s small marina entering a path
Thursday 1115 - Police are unable to find the presenter, so they inform Athens and request assistance from the Greek fire department
1400 - Greek fire services, with six firefighters and a drone team, arrive in Symi
1900 - Helicopter deployed to assist search
Friday - Divers join the search in the water around Symi
Saturday 0600 - Firefighters resume search for Dr Mosley