Divers are searching for TV doctor Michael Mosley after he went missing while on holiday on the Greek island of Symi.
A local Facebook group said Mosley, known for appearing on programmes like This Morning and The One Show, went for a walk from Saint Nikolas Beach at about 1.30pm Greek time on Wednesday.
More people joined the search when it resumed this morning - and Symi deputy mayor Ilias Chaskas said "divers are looking in the water".
Symi's coastguard said around five patrol boats, as well as private and commercial vessels in the area, were now also involved in the operation.
Police and firefighters have also used drones to scan the island, which is about 25 miles north of Rhodes, while a helicopter was deployed at about 7pm local time on Thursday.
The search was paused overnight, but police said "more men will be coming" on Friday.
"The search continues today with seven firefighters, one drone checking the wider area, and we are cooperating with the Hellenic Police Office," a spokesperson for the Greek fire services said.
They also confirmed police are using sniffer dogs in the search for the missing Briton.
Mosley and his wife Clare travelled to the island with another couple on Tuesday for a week's holiday, Kathimerini reported.
The next day, the four of them took a boat and went for a swim at Saint Nikolas Beach - however Mosley preferred to return from the beach on foot, according to the Greek newspaper.
Police are considering all possibilities, including that Mosley had an accident or fall - or suffered a snake bite, Greek news website ekathimerini.com reported.
The area where the presenter went missing is considered "difficult, as it is quite rocky" - Symi mayor Lefteris Papakalodoukas told the news website.
He described the heat on the island on Wednesday as "unbearable and one could easily faint in such conditions".
The mayor added that Mosley "wanted to walk back from the beach, but that's a distance of about an hour-and-a-half", adding: "There are shortcuts he may have taken."
Read more:
What we know about missing TV doctor and his last known movements
A statement from local police, which has been translated, said officers were informed about the "disappearance of the 67-year-old British national on the island" two days ago. It is reported Mosley's wife raised the alarm then.
Police asked for assistance from the Greek fire service, with firefighters, a vehicle and a drone team arriving from Rhodes at about 2pm yesterday.
The rescue operation is focusing on the Pedi area of the island after a woman reported seeing him there on Wednesday.
Another woman in the area said Mosley's disappearance was "strange" as the path he was thought to be on is "clear".
"It's a quiet place… if you see the map of the area it's a clear path, it's nothing dangerous," she said.
"Many people go every day, every few minutes, that's the reason it's very strange because it's a clear path."
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Adriana Shum, who shared the Facebook appeal yesterday, said in a later comment on the social media post that Mosley reportedly "left his phone at his accommodation".
"The police, coastguard and EDOK, the mountain rescue people, are all searching plus all the locals are aware and keeping a look out," she wrote.
"These days it should be pretty difficult to get lost on Symi as so many of the paths have been surfaced and there is a lot more activity even in the most remote areas," she added.
Before the search was halted on Thursday night, she wrote: "Apparently he was sighted at Kamares so he made it that far.
"My husband has just spent 2 hours searching every public route in the valley by torchlight, calling his name, and has now joined EDOK to continue the search."
A Foreign Office spokesman said: "We are supporting the family of a British man who is missing in Greece and are in contact with the local authorities."
Mosley is known for being a columnist for the Daily Mail and has made a number of films about diet and exercise.
The broadcaster fronted the Channel 4 show Michael Mosley: Who Made Britain Fat? and was part of the BBC series Trust Me, I'm A Doctor.
Who is Michael Mosley?
Mosley is known for appearing on television programmes like This Morning and The One Show.
He was one of the presenters of the series Trust Me, I'm A Doctor on the BBC - and also hosts its Just One Thing health podcast.
He also lived with tapeworms in his gut for six weeks for the documentary Infested! Living With Parasites on BBC Four.
Mosley is also credited for the rising popularity of the 5:2 diet for losing weight, which involves fasting for two days per week.
He is also a columnist for the Daily Mail and has made a number of films about diet and exercise.
More recently, he presented two series for Channel 4, Secrets Of Your Big Shop and Who Made Britain Fat?
His programmes have received nominations for RTS and Emmy awards, and he has previously been named "medical journalist of the year" by the British Medical Association.
Mosley has four children with his wife Clare Bailey Mosley, also a doctor, author and health columnist, who wrote the recipe book Fast 800 Easy.
The couple, who have hosted theatre show tours together, recently attended the Hay Festival.
Trust Me I'm A Doctor star Saleyha Ahsan wrote on social media the news was "shocking" and she was hoping Mosley would be "found safe".
"I literally feel sick with worry," Ahsan added. "Don't even know what to say."
On Thursday's edition of The One Show, presenter Alex Jones opened the programme by saying that "lots of us are concerned to hear our friend Michael Mosley has gone missing whilst on holiday in Greece".
"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.
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Timeline of Mosley's disappearance
Wednesday - 1.30pm: Michael Mosley goes for a walk from Saint Nikolas Beach on the Greek island of Symi. The island is part of the Dodecanese island chain and is about 25 miles north of Rhodes.
Wednesday, 3pm: He has reportedly still not returned to the hotel he is staying at with his wife Clare Bailey Mosley - also a doctor, author and health columnist.
Wednesday - 7.30pm: Mosley's wife reportedly raises the alarm and Greek authorities start to retrace his route but do not find him.
Thursday - 11am: An appeal (which appears to have been first posted on Wednesday at 5.34pm) is updated in a local Facebook group called Friends of Symi, which includes a photograph of the 67-year-old TV doctor on a beach wearing a blue T-shirt, grey knee-length shorts, a blue baseball cap and dark sunglasses. He is pictured holding a green rucksack. The post reads: "Have you seen this man? He set off to walk back from St Nick's at about 13.30 and failed to make it home. " It adds: "His name is Dr Mike Mosley and he is a familiar face for many British people." The edit reads: "So far he still has not been found and the search continues."
Thursday - 2pm: Six firefighters, a vehicle and a drone team are deployed from Rhodes to join the search.
Thursday - 7pm: A helicopter joins the search as Greek authorities continue to scour the coast.
Thursday night: Greek police say the search is being paused, but "more men will be coming" on Friday morning. Before the search is halted, Adriana Shum, the person to share the Facebook appeal, says in a comment on the social media post: "Apparently he was sighted at Kamares so he made it that far." She adds Mosley reportedly "left his phone at his accommodation".
Friday - 7am: Police confirm the search has resumed.
Friday morning: The local mayor's office says islanders, a helicopter from Rhodes and Greek officers, along with police drafted in from outside the island, are searching the Pedi area and surroundings. The rescue operation is focusing on that area of the island after a woman reported seeing Mosley there on Wednesday.
Friday - later: The Hellenic National Meteorological Service issues a yellow weather warning for Rhodes and the surrounding islands including Symi for high temperatures, which are forecast to reach highs of 36C (96.8F).
Radio 2 presenter and Channel 5 talk show host Jeremy Vine wrote in a social media post: "I'm praying this lovely man is found and thinking of Clare and the whole Mosley family."
MoneySavingExpert.com founder Martin Lewis wrote on X: "Feeling disturbed about the news about Dr Michael Mosley. I hope he's ok."
