Azerbaijan held a day of mourning on Thursday for the dozens of victims of an airliner crash in Kazakhstan, as questions were being asked over the cause of the disaster.

Azerbaijan on Thursday observed a nationwide day of mourning for the victims of the plane crash that killed 38 people and left all 29 survivors injured as speculation mounted about a possible cause of the disaster, with some experts saying that the airliner was damaged by Russian air defense fire.

The Kremlin urged restraint on Thursday in speculating about the cause of an Azerbaijan Airlines plane crash in Kazakhstan that killed 38 of the 67 passengers on board. "An investigation is currently under way;