Rasuwa bus accident Bus owner's family in bus. Daughter among 12 dead. Photo: Nuwakot FM

At least 12 people, two of them Israeli trekkers on their way to Langtang National Park, were killed when a bus plunged 150 m down a mountainside on the Pasang Lhamu Highway on Friday morning.

The bus was overcrowded with more than 100 passengers, many of them sitting on the roof as the driver negotiated the narrow mountain road damaged by the monsoon rains.

The death toll is expected to rise, as many passengers are still trapped inside the bus. At least 52 of the passengers are injured, seven of them foreigners. Fifty others, most of them travelling on the roof, were thrown off and survived.

Helicopters sent by the Israeli Embassy are at the site to rescue the injured.

This is the fourth serious highway disaster this holiday season. More than 35 people were killed in a bus plunge in Doti, and 12 people were killed separate crashes on the Prithvi Highway and in Makwanpur last week.