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

ToplineRussia accidentally downed an Azerbaijan Airlines flight on Christmas Day and then attempted to cover it up, Azerbaijani President Ilham Aliyev claimed Sunday, though the cause of the deadly crash in Russian air space—killing 38 people—is still unknown.

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.