Bad weather conditions and poor visibility caused crash of the Boeing-727 airplane, owned by Iran Air, in the north-west of Iran, Iranian Roads and Transport Minister Hamid Behbahani said.
He said "the airplane's pilot intended to return to Tehran, but bad weather conditions prevented him to do it."
Behbahani also said that "the pilot died immediately after the crash."
The Boeing-727 airplane, owned by Iran Air, crashed on Sunday in West Azerbaijan Province, Fars news agency reported quoting Medjidi.
Seventy-seven people, including 12 crew members, died, while 26 people were injured and two have been missing, the Fars agency reported Monday morning. Earlier 12 crew members' death was reported.
The representative of West Azerbaijan Province's administration said that last time the pilot had established contact with the dispatcher shortly before the emergency landing and he had announced that the plane had a technical problem on board.
There were difficulties during search operations on the scene due to bad weather conditions.
Iranian President Mahmoud Ahmadinejad has offered his condolences to the families of the crash victims.
In connection with the tragedy a three-day mourning was declared in the Iranian province of West Azerbaijan.
Earlier, Azerbaijani Embassy in Iran, had told Trend, that so far they have no information if were Azerbaijani citizens on board of the crashed aircraft.
Iran has a history of frequent air accidents blamed on its aging aircraft, Press TV reported.
In Jan. 2010 a TU-154 airplane steered by Russian crew crashed at the airport of the Iranian city of Meshhed, leaving 46 passengers injured.
On July 24, 2009, an IL-62 crashed in Iran leaving 16 dead, including 13 crew members. The plane went beyond the runway and collided with a concrete barrier.
On July 5, 2009, a TU-154 airplane en route from Tehran to Yerevan crashed in the suburbs of the Iranian city of Kazvin. All 168 people on board the plane died.