Azerbaijan Airlines says the jet that crashed in Kazakhstan on Christmas Day experienced “physical and technical external interference,” according to an early investigation, as questions swirled about Russia’s possible involvement in the disaster.

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

A passenger jet operated by Azerbaijan Airlines crashed near the city of Aktau in Kazakhstan on Wednesday, after diverting from an area of southern Russia where Moscow has repeatedly used air defence systems against Ukrainian attack drones.