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.”

Russian President Vladimir Putin apologized for the deadly Azerbaijan Airlines Flight 8243 crash on Christmas but did not take responsibility for causing it as an investigation continues into the matter.

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

Two U.S. military officials told NBC News that they had intelligence indicating that Russians may have misidentified the plane and shot it down.

Vladimir Putin has apologised for the Azerbaijan Airlines crash but stopped short of accepting responsibility for what he described as a “tragic incident”.

Russian President Vladimir Putin has apologized to Azerbaijani President Ilham Aliyev following the crash of an Azerbaijan Airlines plane in Kazakhstan that resulted in 38 fatalities, according to the Kremlin.

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

Azerbaijan's president said on Monday that Russia was "guilty" over the downing of an airline last month that Baku says was shot by Russian air defenses. An Azerbaijan Airlines Embraer 190 jet crash-landed in Kazakhstan on Dec.