Johannesburg  - At least 30 people were believed to have died when their bus plunged from an embankment into a gorge in southern KwaZulu-Natal province, emergency services told SAPA news agency.

A large rescue operation was underway to retrieve around 30 people still trapped inside the bus, which was believed to be carrying around 80 people, SAPA reported.

Some of the injured were being treated at the scene, where extra medical personnel were being flown in by army helicopter.

National radio reported the bus skidded off an embankment and plummeted 150 metres into the river in the remote area of steep cliff roads and wooded ravines. (dpa)