Thirty-three people survived, the semi-official Fars news agency reported, quoting the coroner's office of West Azerbaijan province.

Reports said darkness and snow were hampering（妨碍，束缚） rescue efforts.

Earlier reports had said that 50 people survived the crash.

Old planes

The plane was due to land in Orumiyeh, 700km (430 miles) north-west of Tehran.

It crashed near the city at around 1945 local time (1615 GMT), according to another local official quoted on Iranian state television's website.

The official said the plane had taken off an hour later than scheduled, and came down because of bad weather conditions.

A official for the Iranian Red Crescent, Mahmoud Mozaffar, said the plane had broken into several pieces, but there was no explosion or fire.

The head of Iran's emergency services, Gholam Reza Masoumi, told Fars that rescue work was being made more difficult by heavy snow, which was around 70cm (27 inches) deep around the crash site.

There have been a number of accidents involving Iranian planes over the past few years.

The last major crash was in July 2009, when a plane caught fire mid-air and crashed in northern Iran, killing 168 people.

In 2003 an Iranian troop carrier crashed in the south-east, killing all 276 soldiers and crew on board.

Iran's civil fleet is made up of planes in poor condition due to their old age and lack of maintenance