“We’re very worried but we haven’t given up hope. That’s why we’re appealing for witnesses.”

Clare Carlile, a friend of one of Mr Doherty’s daughters, posted a missing person’s appeal on the climbing and mountaineering website UKClimbing on Tuesday evening.

She said: “My friend’s dad has gone missing in the French Pyrenees. Does anyone know where this image is from to try and help locate him? He sent a message at 4pm this afternoon saying he had fallen while hiking and could not move. We have not been able to get in contact with him since.

“He is likely to be in/close to Ariège, in the Occitanie region. His last known location was Étang du Comté, where we have located an image from Sunday.

“The image shared is from Saturday – we are trying to work out his direction of travel in case it gives some idea of where he may be now. He sent a message during the day saying he was ‘somewhere near Ax-Les-Thermes’. We are in contact with the British embassy for France, who are alerting the police.”

Since retiring almost a decade ago, Mr Doherty has spent most of his time in France.

According to his family, the retired doctor was a respected consultant of tropical medicine who worked around the world and specialised in malaria.