Azerbaijan Airlines, the carrier of the passenger jet that crashed in Kazakhstan on Christmas Day, said preliminary investigations have found the disaster occurred “as a result of physical and technical external interference,

The statement is the closest officials have come to confirming mounting suspicions that the plane was downed by a Russian air-defense system.

It comes as the head of Russia's civil aviation agency says the situation in Grozny, the plane's destination, was "very complicated" at the time.