The Airbus A-310 making the overnight flight from Moscow to Irkutsk overshot the runway on landing and tore through a concrete barrier.
An investigator was quoted by the RIA-Novosti news agency as saying a hydraulic brake failure may have caused the crash.
"The information we have shows that after landing, when the plane put on the thrust reverser, there was a failure in the braking system that led other mechanisms in the system to break down," a member of the inquiry set up to look into the causes of the crash said.
"This meant the plane was basically out of control after landing."The aircraft crashed into a compound of garages, stopping near some small houses, in flames, at 7.50am on Sunday.
The official said the reason for the crash would only be established definitively once the black box flight recorders had been examined and tests were carried out on the remnants of the aircraft.
Almost 140 people are feared dead in the crash.
There were two explosions caused by the tonne of fuel in the aircraft, Moscow radio reported.
Irina Andrianova, a spokeswoman for the emergency situations ministry, said it took firefighters more than two hours to put out the fire.
Rescue workers recovered 118 bodies, a duty officer in the regional branch of Russia's emergency situations ministry said.
At least 68 people survived the
crash, but most were injured
He said 68 people were known to have survived the crash; 53 were hospitalised with burns and smoke poisoning.
Six people were in critical condition, including a 10-year-old child, the medical emergencies centre in Irkutsk was quoted as saying by RIA-Novosti.
Fourteen people were unaccounted for.
Itar-Tass news agency reported that a total of 200 passengers, including eight crew, were on board Sibir airlines Flight 778. Many of them were children flying for holidays on Lake Baikal.
Igor Levitin, the Russian transport minister, said the aircraft's pilots had told air traffic controllers they had landed successfully but then radio contact broke off suddenly.
Levitin, speaking before flying from Moscow to Irkutsk, told Russian state television: "The aircraft veered off the runway. There was rain, the landing strip was wet. So we'll have to check the clutch and the technical condition of the aircraft."
He said the aircraft's two black boxes had been recovered and were being analysed.
The aircraft was flying from
Moscow to Irkutsk
The prosecutor-general's office said investigators considered a technical fault or human error as the two most likely reasons for the crash, news agencies reported.
Alexander Zyubr, an airline official, said the aircraft was in good technical condition, according to RIA-Novosti.
Television pictures from the scene showed the smoking ruins of the jet after it had hit garage buildings. Only the tail section was intact.
About 600 rescue workers were at the scene. Rescue teams, working in rainy weather and poor visibility, used cutting equipment to recover bodies from the wreckage.