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

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

The Kremlin has said that Putin "apologized for the tragic incident" and expressed his "deep and sincere condolences" the the victims' families.

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.

Azerbaijan says the plane had multiple holes in its fuselage and that the occupants had sustained injuries ‘due to foreign particles penetrating the cabin mid-flight’

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.

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.”

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

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