Islamabad  - Thirty-four people were feared to be dead after a bus plunged Thursday into a raging river in Pakistan's northern mountains, officials and police said.

The bus carrying 35 people, including 27 soldiers on leave, was travelling to the town of Skardu, around 800 kilometres north-east of the capital, Islamabad.

It fell several hundred metres into the Indus River near the Rondo area, about 80 kilometres short of Skardu.

"When the bus reached the top of a steep slope, it stalled, causing a failure of the hydraulic braking system," said Akhtar Abbas, a spokesman for the bus service. "The vehicle came hurtling back and plunged into the swift-running river."

"It is next to impossible for someone to survive such a fall," Abbas said.

One person did, however - a bus conductor lived and was taken to hospital.

Rescue workers and local people were trying to recover the remaining passengers from the river but their efforts were hampered by strong currents, police said.

It was believed that all the bodies were swept away.

Fatal road accidents are common in Pakistan because of poor road conditions, unsafe driving practices and improper maintenance of vehicles. (dpa)