Azerbaijan’s leader on Monday accused Moscow of carrying out a “cover up” over a passenger jet crash last month that claimed 38 lives, as relations sour between the two neighbors.

Azerbaijan’s President Ilham Aliyev said Sunday that the Azerbaijani airliner that crashed last week was shot down by Russia, albeit unintentionally. Aliyev told Azerbaijani state television the aircraft was hit by fire from the ground over Russia and rendered uncontrollable by electronic warfare.

The Azerbaijan Airlines plane was en route from Baku to Grozny when it turned toward Kazakhstan and crashed while attempting to land on Wednesday.

Russian President Vladimir Putin apologized to the President of Azerbaijan for the crash of the civilian airliner that killed 38 people, the Kremlin said Saturday, stopping short of admitting responsibility.

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

In the crash’s aftermath, Azerbaijan has unleashed rare and stinging criticism of Russia, with the country’s president saying Moscow’s response has caused “surprise, regret and rightful indignation.”

"The blame for this disaster lies with representatives of the Russian Federation," Ilham Aliyev said on Jan. 6.

Azerbaijan's president has confronted Putin over the devastating plane crash that killed 38 people on Christmas Day.