At least six people died and around 20 were injured when a plane crash-landed in Russia yesterday in heavy fog, officials and the carrier said.

The Tu-134 with 57 people on board was flying from the Siberian city of Surgut to Samara on the Volga river, where it crashed as it was trying to land at the airport.

"The fog was very heavy and the plane's wing touched the ground," said an Emergency Ministry spokeswoman. "Its fuselage then collapsed and it crash-landed."

Reuters pictures showed the wrecked plane lying in two pieces, one upside down, off the runway.

Crash survivors said it took 15 to 20 minutes before rescuers and ambulances started the operation.

Russian news agencies quoted the prosecutor-general's office as saying it was probing whether the crash-landing could have been caused by a pilot error as the plane first touched the ground some 400 metres off the landing field.

But the aircraft's owner, Russian carrier Utair, blamed the fog. He said seven people died and around 20 were taken to hospital. Utair said 50 passengers and seven crew were on board, some 30 of whom escaped unhurt. The emergency ministry said there were six dead.

The airport of Samara, which earlier cancelled all flights and evacuated people from the airport building, said normal operations resumed yesterday afternoon.

Utair, which has over 130 aircraft, was among nine carriers that Russia banned last month from operating charter flights to the European Union, citing safety reasons.

The short-haul Tu-134 is one of the oldest passenger aircraft in service in Russia and some experts have called for it to be withdrawn as soon as possible.