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.

Pakistan's army says it has freed more than 300 hostages from a passenger train seized by militants in Balochistan province on Tuesday. The military spokesperson said 33 militants were killed during the operation.

The fate of hundreds of passengers remained unknown more than 24 hours after separatist militants in Pakistan’s restive southwestern Balochistan province seized a train carrying more than 400 people,