One searcher told the Telegraph: “The path is not easy to follow, if he took a wrong turn, he would be lost. He could be anywhere; it is a race against time.”

Symi’s mayor, Eleftherios Papakalodoukas, told The Sun the area was hilly, rocky and treacherous, and offered no shade from the 40-degree-Celsius temperatures.

The TV presenter and healthy living advocate, who has endorsed fasting and offered tips on sleep and diet, was last seen at 1.30pm on Wednesday.

He disappeared after he set out on a stroll in searing temperatures along a rocky coastal path from Agios Nikolaos beach to the village of Pedi. Mosley did not have his mobile phone with him, hampering tracing efforts.

Police, the fire brigade, the coast guard and volunteers have been searching on and off the island in the eastern Aegean assisted by a helicopter, drones and rescue dogs.

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“The search continues,” spokeswoman Constantina Dimoglidou told Reuters. “We are investigating on foot another rocky part, the wider area of Agia Marina.”

Divers were also involved in the operation and vessels sailing nearby were on alert.

Papakalodoukas said the images and video footage from security cameras had helped sketch out what authorities believed was Mosley’s possible route, which he described as “unconventional”.

They indicated that he may have continued further through Pedi into another challenging area around Agia Marina, the mayor said.

“He chose paths which are very difficult to walk in such temperatures and under any circumstances,” Papakalodoukas said. “Cameras show that he did not take the expected way back home.”

Symi, part of the Dodecanese island chain, is about 16 kilometres long and has 2500 residents. Its remote beaches were filled with sunbathers on Friday.

Mosley has appeared on programs including the BBC series Trust Me, I’m a Doctor, the BBC’s The One Show, and ITV’s This Morning.

Reuters