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 prime minister has commended the country’s armed forces for successfully rescuing 339 passengers after a deadly train hijacking by insurgents in the southwest

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.

After more than a day of fighting with separatist militants who hijacked a train carrying hundreds of passengers, Pakistan’s army said it had brought the insurgent attack to an end, but that 21 passengers and four paramilitary personnel had been killed.

Baloch separatist militants blew up a railway track and launched rockets at the Jaffar Express, which was carrying over 400 passengers.

Hostages freed after a day-long ordeal following an attack by militants on a train in Pakistan's Balochistan province described crouching on the floor for hours before their release, as the bodies of 25 people killed arrived in Quetta.