Emergency teams in the Iranian city of Mashhad are attending the scene of a landing accident involving a Tupolev Tu-154M on a domestic service.
Images from the scene show the aircraft is resting on its fuselage underside, with both wings and the landing-gear torn away.
The jet has suffered heavy fire damage at the rear, where the aircraft's three engines are mounted, and the vertical fin and horizontal stabiliser are no longer attached.
The Tu-154 was performing services for Iranian carrier Taban Air, although the fuselage colour scheme shows that the aircraft is from the fleet of Russian carrier Kolavia. It also carries the name 'Surgut' in Cyrillic on the nose, identifying the jet as RA-85787.
Iran's official state media, citing the Iranian Civil Aviation Organisation, reports that the aircraft was conducting flight 6437 from Abadan to Mashhad but diverted initially to Isfahan because of poor weather.
It resumed its journey to Mashhad but landed in conditions of low visibility, whereupon the aircraft broke up and caught fire. The Tu-154 had 156 passengers on board, but while at least 20 are reported injured there are no indications of fatalities.