The incident occurred at around 13:30 local time (10:00 GMT) in a remote, mountainous area about 58km (36 miles) south of the Qiz-Qalasi Dam and 2km south-west of the village of Uzi, according to Iranian officials and photographs published by state media.

But it was not until after 16:00 local time (12:45 GMT) that Iranian state TV reported that the helicopter carrying the president had experienced what it called a “hard landing” while flying to Tabriz in heavy fog and rain.

Interior Minister Ahmad Vahidi later confirmed that the president’s delegation had been travelling in a convoy of three helicopters and that his aircraft was “forced to make a hard landing due to bad weather conditions and fog in the area”.

He said multiple rescue teams were heading to the area but that fog, snow and rain and the local terrain were hampering the search operation.

As for the other two helicopters that were flying alongside the president's helicopter, they had initiated a search for 15 to 20 minutes after communication was lost. They were then forced to make emergency landings, an official told state TV as the operation continued into the night.

Vice President for Executive Affairs Mohsen Mansouri also said contacts had been made with two people on the president’s helicopter - a flight crew member and one other individual.

"This indicates that the severity of the incident was not very high, as two of the individuals inside the helicopter managed to communicate with our team multiple times,” he added, without providing further details.

However, any hopes that Raisi and his entourage had survived were dashed after daybreak on Monday.