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.

The train hijacking in south-western Pakistan represents a major escalation in the region’s long-running insurgency.

Mehboob Hussain was riding the train home on Tuesday when the tracks under the front car exploded. In the depths of central Pakistan's Bolan Pass, a pocket of wilderness so remote that there is no internet or mobile network coverage, the nine-coach Jaffar Express ground to a halt. Then the bullets started flying.