Iranian search and rescue teams have reached the site of a plane crash which authorities say killed all 65 people on board, according to reports.

The Aseman Airlines ATR-72, a twin-engine turboprop used for short-distance regional flying, went down on Sunday in foggy weather, crashing into Mount Dena in a remote area of southern Iran. The airliner said all on board Flight EP3704 were killed, including six crew members.

The crash of the aircraft, brought back into service only months ago after being grounded for seven years, was yet another fatal aviation disaster for Iran, which for years was barred from buying necessary aeroplane parts due to Western sanctions over its contested nuclear programme.

Press TV said search teams reached the crash site before dawn on Monday. The station said the weather had improved, though it is still windy.

A rescue helicopter flies over the Dena mountains while searching for wreckage (Tasnim News Agency/AP)
A rescue helicopter flies over the Dena mountains while searching for wreckage (Tasnim News Agency/AP)

The TV broadcast footage of a helicopter joining the search and showed ambulances and rescue vehicles preparing to reach the site on Mount Dena, which is about 14,400ft high. The crash site is reportedly at a height of 11,500ft.

Other Iranian news outlets and officials did not confirm that the crash site had been reached. State radio said five helicopters and five drones are active in the search operation. Iran’s semi-official ISNA news agency said that more than 150 climbers have joined the operation.

Transport minister Abbas Akhoundi left Tehran on Monday to visit the site of the crash, state TV reported. Footage posted on independent news websites showed him in the cockpit of a plane taking part in the search. State TV quoted him as saying the cause of the crash was still “not clear”.

High winds have made it difficult to fly helicopters and drones, hampering search efforts.

Rescuers search for wreckage in the Dena mountains (AP)
Rescuers search for wreckage in the Dena mountains (Tasnim News Agency/AP)

The 2015 nuclear accord with world powers lifted international sanctions on Tehran in exchange for curbs on its nuclear enrichment scheme, allowing Iran to purchase planes and parts. The country has since signed deals to purchase tens of billions of dollars’ worth of new aircraft. However, US president Donald Trump’s refusal to re-certify the deal has injected uncertainty into those sales.

The ATR-72 went down near its destination, the southern city of Yasuj, some 485 miles south of the capital, where it took off.

It was not immediately clear what caused the crash, although weather was severe. Dense fog, high winds and heavy snow in the Zagros Mountains made it impossible for rescue crews in helicopters to reach the site in the immediate aftermath, state TV reported.

Aseman Airlines spokesman Mohammad Taghi Tabatabai told state TV that all on board Flight EP3704 were killed. The plane had 59 passengers and six crew members, the state-run IRNA news agency reported, lowering the initially-reported death toll of 66.

The United States expressed condolences over the crash in a Farsi-language statement posted on social media.