Russian federal investigators believe an engine fault probably caused the crash of a Russian airliner near the city of Perm with the loss of 88 lives.
The Boeing 737-500, which belonged to Aeroflot subsidiary Aeroflot Nord, caught fire in mid-air as it came in to land on a flight from Moscow.
Lead investigator Alexander Bastrykin linked the crash to "technical failure and a fire in the right engine".
The plane's flight recorders have been found and will be analysed.
Crash victim Gen Troshev (l) advised Vladimir Putin on Cossack affairs
Giving his preliminary opinion, Mr Bastrykin, head of the federal prosecutors' Investigative Committee, told Russian media there was "much evidence" for the engine fault theory.
Russia's Transport Minister, Igor Levitin, said he had no information to suggest the cause of the crash had been a terrorist attack, or that the plane had exploded in mid-air.
Relatives of some of the dead have arrived in Perm and are being looked after by the local authorities.
There were 82 passengers on board, including seven children, and six crew.
Those killed include Gen Gennady Troshev, a former commander of Russian forces in Chechnya, and 21 foreign citizens - nine people from Azerbaijan, five from Ukraine and one person each from France, Switzerland, Latvia, the United States, Germany, Turkey and Italy.
Contact with the plane was lost at 0521 Perm time on Sunday (2321 GMT Saturday) as the plane was coming in to land at a height of 1,100 metres, Aeroflot said.
The minister for security in the region said the plane had caught fire in the air at an altitude of 1,000 metres.
It crashed on the outskirts of Perm, just a few hundred metres from residential buildings, but no-one was hurt on the ground.
Part of the Trans-Siberian railway was shut down as a result of damage to the main east-west train track and the blaze took two hours to extinguish.
An eyewitness said the descent of the plane had looked like a "burning comet".
"I felt an explosion - I felt as it threw me up from the bed maybe half a metre up. Then my daughter ran in from the next room crying: 'Has a war begun or what?'" the unnamed woman told Russian TV.
"As the witness and neighbours are saying, it started burning still in the air.
"It looked like a comet, a burning comet. It hit the ground opposite the next house, there was a blaze, like fireworks, it lit the whole sky, the blaze."
Russian federal prosecutors have launched an inquiry to examine whether safety procedures were violated.
Aeroflot says the plane had "a full technical inspection" early this year and was judged to be in a "proper condition".
Aeroflot conducted its own investigation into the causes of the crash and, without giving details, announced it was stripping Aeroflot Nord of the right to use its name from Monday onwards.
"We have paid too high a price for lending out our flag," said Aeroflot's managing director, Valery Okulov.
Sunday's accident was the deadliest involving a Russian airliner since 170 people died in August 2006 when a Tupolev-154 bound for St Petersburg crashed in Ukraine.
Correspondents say the tragedy will be a setback for Russian aviation, which has been trying to shake off a chequered safety record.
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