Russian President Vladimir Putin apologised on Saturday over the crash of an Azerbaijani Airlines plane, though he stopped short of accepting that it might have been hit by Russian fire.

T hursday is an official day of mourning in Azerbaijan as an investigation is underway to determine what caused an airplane carrying 67 passengers to crash on Christmas Day in Kazakhstan, killing 38 and leaving at least 29 survivors. Video posted by CNN shows the plane crash-landing, exploding into a fireball and plumes of black smoke.