MOSCOW (Reuters) - An explosion at military training site in western Russia killed six airborne troops and left two more injured on Tuesday, state-run RIA news agency said, quoting the country's Defence Ministry.

"Six airborne forces troops were killed as a result of the explosion. Two more military personnel suffered injuries and were moved to the nearest medical institution," RIA quoted the ministry as saying.

It was not clear what caused the explosion on the military training site in the Pskov region where the soldiers were returning from fire exercises.

(Reporting by Gabriela Baczynska; editing by Barry Moody)