The death toll from a militant hijacking of a train in Pakistan's southwestern mountains has risen to 31 soldiers, staff and civilians, the military said on Friday as it accused India and Afghanistan of backing the insurgents.

Separatist militants fired at a passenger train in southwestern Pakistan on Tuesday, injuring a train driver, police and railway officials said.

Director General Lieutenant Gen Ahmed Sharif Chaudhry said 26 hostages were killed by the terrorists before the start of the army operation.