Russia's aviation watchdog said on Friday that an Azerbaijan Airlines plane which crashed in Kazakhstan on Wednesday had decided to reroute from its original destination in Chechnya amid dense fog and a local alert over Ukrainian drones.

Rosaviatsia, the wathdog, said that the captain of the plane had been offered other airports at which to land, but had chosen Kazakhstan's Aktau. It said that it would provide comprehensive support to Kazakh and Azerbaijani investigations looking into the crash.

Russia has said it's important to wait for an investigation to finish its work to understand what happened. Four Azerbaijani sources told Reuters on Thursday the plane had been struck by Russian air defences.