The bus swerved off an unfinished stretch of road and plummeted 300 metres into the fast-flowing water below, said Lokendra Shrestha, a police officer in Sindhuli district, around 80 kilometres (50 miles) east of Kathmandu.

"Forty-three dead bodies have already been recovered and the bus has been destroyed. It is likely that more bodies will be found near the crash site, which is very remote," said Shrestha.

A group of 11 passengers who had been on the roof jumped before the bus fell into the Sunkoshi River, said chief district officer Beni Madhav Gyawali.

A number of injured passengers were hospitalised, two of them in critical condition.

Road accidents are relatively common in Nepal due to poor roads, badly maintained vehicles and reckless driving.