A plane that crashed on April 2 into a snowy field in Siberia, killing 31 people, appears to have been improperly de-iced, officials said.
But Alexander Neradko, the head of Russia's civil aviation department, Rosaviatsiya, also said there was no indication that negligence caused the crash.
Investigators said evidence so far suggests a technical failure as the cause.
The twin-engine turboprop belonging to UTair crashed shortly after takeoff from the snowy western Siberian city of Tyumen with 43 people aboard.
Twelve people have been hospitalized in serious condition.
The plane was flying to the oil town of Surgut when it went down.
Russian workers carry out rescue operations at the site of the crash near Tyumen on April 2.
Russian natural gas company Surgutneftgaz said several company officials were on board.
UTair, the privately-owned airline operating the flight, said in a statement that the plane crashed shortly after takeoff while conducting a "forced landing" 1 1/2 kilometers outside Roshchino Airport.
UTair said it would pay 2 million rubles ($67900) to the relatives of each crash victim.
"We have set up an operational headquarters and committed all the necessary resources," Tyumen Oblast Governor Vladimir Yakushev said at the site of the crash.
"As you can see, investigators and transport police are working on the site," he continued. "They are documenting the scene now. The main task now is the identification [of the victims] and notifying their next of kin."
Based on reporting by AP, AFP, Reuters, and ITAR-TASS