Russian investigation authorities have ruled out terrorism as cause of the crash of the Defense Ministry's Tupolev-154 airplane, Tass news agency reported.

    Federal security service FSB said the investigators probing into the causes of last Sunday's crash are proceeding along four main lines of inquiry. "The four main versions are an engine being hit by a foreign object, substandard fuel that caused the loss of thrust on and eventually stopped the engines, the pilot's mistake and the plane's technical failure," the FSB said. 

    "At this point there is no evidence or trace that might point to the possibility of a terrorist attack or sabotage on board. "By now several witnesses of the plane's crash have been established. Also, there is a file retrieved from a car video recorder. The investigators are questioning the witnesses and examining the video," the FSB added. 

    There were 92 people on board the aircraft, including eight crew members.

Source: QNA