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.

Russian President Vladimir Putin apologized for the “tragic incident,” which left 38 people dead, though he stopped short of taking responsibility.

Azerbaijan President Ilham Aliyev said Russia is behind the Christmas Day crash of an Azerbaijan Airlines plane in Kazakhstan, which killed 38 of the 67 people aboard. The motives of the incident remain unclear.

Russia's leader apologises over the downing of an Azerbaijani plane in Russian airspace - without directly taking blame.

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 devastating crash of an Azerbaijan Airlines Embraer 190 near Aktau has left the world searching for answers. New images reveal signs of possible sabotage, with shrapnel marks and allegations of electronic warfare targeting the aircraft.