The apology from Russian President Putin came as allegations mounted that the plane had been shot down by Russian air defenses.

Russian President Vladimir Putin apologized to his Azerbaijani counterpart after an incident in Russian airspace that led to the crash of an Azerbaijan Airlines passenger aircraft on Dec. 25, killing dozens.

Vladimir Putin admitted Saturday Russian air defence was working when an Azerbaijani Airlines plane tried to land in Grozny before crashing, breaking the Kremlin's silence as speculation mounted Russia may have accidentally shot the plane.

Russians who reviewed the transcript of the crew's conversations from the Baku-Grozny flight themselves admit that the air crash was caused by their air defense systems (ADS), according to Andriy Kovalenko,

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 White House said Friday there were "early indications" that Russian air defenses downed an Azerbaijan Airlines flight in Kazakhstan.

The Russian leader’s phone call stopped short of acknowledging responsibility for the crash of an Azerbaijan Airlines plane.

The Azerbaijan Airlines Embraer 190 plane was flying from Baku to Grozny on Christmas Day when it diverted across the Caspian Sea and crash-landed near Aktau, Kazakhstan, killing 38 of the 67 people on board.

The Kremlin said Putin had "offered his apologies that the tragic incident had occurred in Russia's airspace."