Azerbaijani President Ilham Aliyev said on Sunday that the passenger plane that crashed in Kazakhstan killing 38 people had been damaged due to shooting from the ground in Russia, Azerbaijan state television reported.

Four sources with knowledge of the preliminary findings of Azerbaijan's investigation told Reuters that Russian air defences mistakenly shot it down.

Putin apologized for the “tragic incident” that occurred in Russian airspace, but the Kremlin did not take responsibility for downing the Azerbaijan Airlines flight.

The Azerbaijan Airlines plane flew hundreds of miles off its scheduled route from Baku to Grozny, and crashed on the eastern shore of the Caspian Sea. Russia's aviation watchdog said a bird strike might have been the cause.