Kathmandu - At least 22 people, among them schoolchildren, were killed and dozens more injured after an overcrowded bus fell into a river in western Nepal, police said Friday.

Police said the bus plunged into Narayani River after smashing into the guard rail of a bridge while trying to overtake a tractor on Thursday night in Nawalparasi district, about 200 kilometres west of the capital Kathmandu.

Police said at least 22 people were killed and more than 60 others were inured in the accident. The bus was carrying students and teachers who were returning home after a picnic in the nearby town of Butwal.

Many of the victims died after being trapped in the mangled wreckage of the bus.

Police added they faced difficulties in rescuing many of the survivors due to darkness, lack of proper rescue equipment adn the fact that bus broke into several pieces after it smashed into the river bed.

Many of the survivors were rushed to hospitals in Kathmandu and nearby towns in serious condition, raising fears that death toll could rise further.

Initial investigation into the accident showed that the driver had been speeding and police was also looking into whether the he was driving after consuming alcohol.

Nepal has seen a spate of bus accidents in recent weeks which have killed at least 40 people.

Hundreds of people are killed in accidents involving public transport across the Himalayan nation each year, blamed mostly on reckless driving and disregard for safety regulations. (dpa)