The wife of missing TV doctor Michael Mosley has vowed her family "will not lose hope" as she described the days since his disappearance as "the longest and most unbearable".
Update:
Body found in Mosley search
The statement by Dr Clare Bailey Mosley came as the couple's four children arrived on the Greek island of Symi and the focus of the extensive search for the broadcaster shifted to a snake-infested mountainous area after CCTV footage emerged of his last known movements.
As the rescue effort continued amid soaring temperatures, one emergency worker said it was "a race against time".
Making her first public comments, Dr Bailey Mosley said: "It has been three days since Michael left the beach to go for a walk. The longest and most unbearable days for myself and my children.
"The search is ongoing and our family are so incredibly grateful to the people of Symi, the Greek authorities and the British Consulate who are working tirelessly to help find Michael.
"We will not lose hope."
Symi's mayor has said there is "no chance" the search, which has involved helicopters, drones and divers, will be called off until the 67-year-old is found.
But while Eleftherios Papakaloudoukas said he hoped the Briton would be found safe, he questioned how anyone could survive in the heat that topped 40C (104F) on the day he vanished.
He pointed out a search dog was only able to work for an hour on Saturday morning due to the temperature.
Read more about missing TV doctor:
What we know about his last known movements
Son reveals surreal parallels with case of missing dad
Sniffer dogs find heat unbearable in hunt for Mosley
Sadiya Chowdhury
News correspondent
Even with bright red rescue suits on, the small search team looking for Dr Michael Mosley is hard to spot on the vast rocky terrain that surrounds the Pedi marina.
The group of five scan the designated search area, narrowed down to a small patch north of the marina.
It is now three whole days since Mosley went missing and this is the only team we have encountered today.
The local mayor insists it's a large-scale search operation with 100 workers and more teams due to arrive from neighbouring islands.
He promises there'll be a thermal-imaging helicopter arriving soon too as he admits the sniffer dogs are finding the heat unbearable.
It is above 30C (86F) here, and the search team are in full gear - overalls, mountain boots and helmets.
"Very hot," one of them says as they return to their base.
They've been up there for three hours and their search has yielded no results.
But this area, she explains, is very dangerous.
Would she recommend it as a trekking route?
"No, absolutely not. Not without equipment and special shoes."
For today, she says, this team's work is done.
They'll be back tomorrow to search a different region.
Mosley has not been seen since Wednesday after he left his wife and another couple and set out alone from Saint Nikolas Beach to walk back to their friends' home in Symi Town.
He was later caught on a security camera as he made his way through the small fishing village of Pedi, around 1.2km away, which appeared to show him heading up into remote rocky terrain and in the wrong direction to the island's capital.
His wife raised the alarm after he failed to return.
One rescuer said: "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."
The search for Mosley resumed early on Saturday, with teams scouring a 6.5km radius over a mountainous landscape, which search organisers described as "very dangerous".
Mr Papakaloudoukas said the area the missing is believed to have ventured into is "only rocks" and "difficult to pass", with "loads" of snakes.
He added: "He chose paths which are very difficult to walk in such temperatures and under any circ*mstances."
Authorities have considered a number of possibilities for Mosley's disappearance, including that he may have suffered a fall or been bitten by a snake, according to reports.
He did not have his mobile phone with him, hampering efforts to find him.
Mosley, his wife and the other couple are understood to arrived in Symi for a week's holiday on Tuesday.
Mosley is a columnist and presenter who has made a number of films about healthy living.
Known for popularising the 5:2 diet, he fronted the Channel 4 show Michael Mosley: Who Made Britain Fat? and was part of the BBC series Trust Me, I'm A Doctor.
He has also appeared on numerous daytime television shows and hosts the health podcast, Just One Thing.
