Officials initially said there were four people aboard the air force Mi-8 helicopter, but three Russian news agencies later quoted air force spokesman Alexander Drobyshevsky as saying there were nine on board and that eight were killed.

The crash on Saturday killed three crew members and five border guards who were passengers, Drobyshevsky said.

He said the surviving passenger was flown to the main Russian military base in Chechnya and hospitalised there.

Citing unnamed air force officials, the RIA-Novosti news agency reported that preliminary information indicated the helicopter flew into a mountainside, wording that suggested authorities did not believe it was shot down.

RIA-Novosti said the helicopter had taken off from Khankala, the main Russian military base in Chechnya. 
Chechen fighters have shot down several Russian helicopters over the region during the two wars there in the past decade, and others have crashed because of technical problems or pilot error.