A massive search operation is underway for British TV producer and journalist Michael Mosley, who went missing in the mountainous region of the Greek island of Symi on 5 June.

The 67-year-old doctor is best known for his appearances on BBC’s The One Show and ITV’s This Morning. He was a proponent of the 5:2 diet plan and supported intermittent fasting through his programs.

According to reports, Mosley went missing after going for a walk along the coastal path between Agios Nikolaos beach and the village of Pedi.

He was last captured on CCTV holding an umbrella walking through Paddy around 30 minutes later, indicating he had not been involved in an accident on the coastal path. A police officer who spoke to BBC News said Mosley appeared to be in good condition and walking at a steady pace in the footage, but said no trace of him had been found.

An extensive search was launched Thursday by police, the fire department and the coast guard on the small island in the eastern Aegean Sea near Turkey after Mosley’s wife reported him missing.

Some local officials had earlier suspected that Mosley may have fallen into the sea. However, CCTV footage ruled out this possibility. Police also investigated the possibility that he may have spoken to locals while walking along the coastal path, but they found no clues.

Symi mayor Lefteris Papakalodoukas described the incident as “very strange”, saying it was a 10-minute walk from the beach to Pedi and would take 40 minutes to reach the main road.

“You cannot disappear, you cannot get lost,” the mayor was quoted as saying by news agency Reuters.

The mayor analysed Mosley’s route based on CCTV footage and said he may have continued walking after reaching the challenging area around Agia Marina from Peddie.

“They chose routes that were very difficult to follow in such temperatures and under any conditions. The cameras show that they did not take the expected route to return home,” he said.

Police have also deployed drones and helicopters to aid the search and are planning to focus the operation on areas around Paddy. Members of Mosley’s family, including his four children, have flown to the Greek island to assist search teams.

Symi is a sparsely populated rocky island, about 10 miles long and home to about 2,500 inhabitants.