Chinese President Xi Jinping on Thursday sent condolences to the presidents of Azerbaijan, Russia and Kazakhstan for the casualties caused by the Azerbaijan Airlines plane crash, China's state broadcaster CCTV reported.

The flight was en route from the Azerbaijani capital of Baku to Grozny, in Russia’s south, when it diverted and attempted an emergency landing in Kazakhstan.

"No one claims that it was done on purpose," an Azerbaijan official told Reuters. They added their government "expects the Russian side to confess."

National flags were lowered across Azerbaijan, traffic across the country stopped at noon, and signals were sounded from ships and trains as the country observed a nationwide moment of silence.

Azerbaijan is observing a nationwide day of mourning for the victims of the air crash that killed 38 people and left all 29 survivors injured as speculation mounted about a possible cause of the crash

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.