At least 28 people died in a collision between a methanol tanker and a bus on a motorway in northern China on Sunday, state media said.

The two vehicles caught fire after the collision, which happened about 2:00 am at Yanan city in Shaanxi province, Xinhua reported.

Emergency services were still verifying the number of casualties, who were mainly in the 39-seat bus, the news agency added.

Three people survived with injuries, and two were taken to hospital. A total of 28 bodies were pulled from the debris.

Details of the crash -- which happened 200 metres (yards) from a motorway service station -- were still unclear.

Police were investigating the cause of the accident which happened on the Baotou-Maoming Expressway, a motorway which spans the length of China from the southern province of Guangdong to Inner Mongolia in the north.

Vehicles carrying explosive materials must first get permission from the police before travelling on the roads in China.

China's roads are highly dangerous, with traffic laws and safety widely flouted, and truck drivers typically overworked.

Last year more than 62,000 people died in traffic accidents, state media said, citing police figures.