'The exact spot of the plane crash was not found, and given the darkness, heavy snowfall and fog in some regions, the aerial search operation was stopped and will be resumed tomorrow, Esmaeil Najjar, head of Iran's Crisis Management Organisation, told the ISNA news agency. The plane had 59 passengers and six crew members, the state-run IRNA news agency reported late Sunday, lowering the initially reported death toll of 66.
"The Revolutionary Guards' helicopters this morning found the wreckage of the plane on Dena mountain", a spokesman, Ramezan Sharif, told state broadcaster Islamic Republic of Iran Broadcasting (IRIB).
Aseman Airlines, owned by Iran's civil service pension foundation, is a semi-private air carrier headquartered in Tehran and is Iran's third-largest airline by fleet size, behind state carrier Iran Air and Mahan Air.
After a long wait to locate the plane, families would have to endure further delays until the bodies of their loved ones were returned as helicopters were unable to land in the hostile terrain and the work would have to be carried out on foot, an emergency service official said.
The Revolutionary Guards said drone images had helped locate the wreckage before two air force helicopters were dispatched.
'Even newer versions of this aircraft are not good for such cold places and it would be better not to use it for this route and especially with such bad weather and visibility, he said.More news: Gun owner destroys AR-15 in Facebook video after Florida school shooting
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Snowmobiles were deployed earlier on the 4,409-metre (14,465-foot) peak, where more than 100 mountaineers have also been aiding the search.
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 southern Iran.
Aseman Airlines was blacklisted by the European Commission, in December 2016, over safety concerns.
Sixty-five people were on board, according to Iranian state media.
Iran has suffered several plane crashes in the past few decades and has blamed USA sanctions for preventing it from importing new aircraft or spare parts.
However, US President Donald Trump's refusal to recertify the deal has injected uncertainty into those sales.