"According to preliminary conclusion by the teams of investigators, no sings of terrorist attacks have been found," the Russian federal security service FSB spokesman Sergei Ignatchenko told Itar-Tass.

Several versions of the accidents are under consideration, the main of them being - illegal intervention in the activity of civil aviation or breach of operation regulations of the aircraft that resulted, through carelessness, in the death of passengers, Ignatchenko said.

At present, all the charter- and flight recorders of the crashed planes have been found and brought to Moscow. Specialists are now examining them, the spokesman said.

Source: Itar-Tass