A packed bus, with passengers also travelling on its roof, has plunged over a cliff and killed at least 30 people in central Nepal, officials have said.

Police said they were investigating the accident which occurred on Tuesday about 80km northwest of the capital, Kathmandu.

Rescuers struggled to recover bodies and help the injured to safety after the bus fell 200 metres off the mountainous road in Rasuwa district, home to the popular Langtang trekking route.

"Of the 30 dead, 29 were recovered from the accident site and one died while undergoing treatment," district chief Shiva Ram Gelal was quoted as saying by the AFP news agency.

"We have sent 35 other people who were wounded to nearby hospitals and we are continuing to search the area."

The official said the bus had a large amount of passengers because of the severe fuel shortage that has hit the country which has forced people to travel on the roofs of buses.

Ethnic protesters have blocked a key border point with India since September, which has prevented the import of fuel and other supplies.

Source: Agencies