A traffic accident that killed 36 people and injured three in Northwest China's Shaanxi province on Sunday was the fault of the drivers, the traffic management bureau of the Ministry of Public Security said on Wednesday.

Yang Jun, director of the bureau, said preliminary investigations have shown that the drivers of the sleeper bus and the methanol tank it rammed into broke traffic laws and regulations and the accident has exposed a number of weak points in traffic safety.

"The management for traffic safety did not work properly and the hidden dangers, which have existed for a long time, have not been effectively resolved, which we must pay greater attention to," the director said.

A China Daily reporter discovered that the driver of the sleeper bus could have been driving fatigued, having not stopped for a rest at night, contrary to regulations.

The tanker driver was not properly trained in dangerous goods transport.

Wang Dexue, deputy director of the State Administration of Work Safety and head of the work group sent by the State Council, said driver fatigue was the major cause of the accident and there was no effective measure to force long distance buses to stop for a rest between 2 am to 5 am.

At about 2:40 am on Sunday, a double-decker sleeper bus from Hohhot, capital of the Inner Mongolia autonomous region, to Xi'an, capital of Shaanxi province, rammed into a tanker carrying methanol, a highly flammable liquid, and caught fire on a highway in Yan'an.

Thirty-six people were killed on the bus and three escaped with injuries. The two drivers of the tanker were not harmed.

According to Liang Hongxian, mayor of Yan'an, the tanker from Henan province had just left the highway's Ansai service area and was hit by the sleeper bus about 73 meters from the service area.

After the accident occurred, the State Council sent a work group composed of officials from the Ministry of Public Security and the State Administration of Work Safety to Yan'an to investigate the accident and deal with the aftermath.

Prosecutors from the Supreme People's Procuratorate who investigate misconduct by officials also took part in the investigation. People found to have criminal responsibility for the accident will be prosecuted.

According to the mayor, DNA identification of the 36 victims had been completed, and 137 members of the victims' families had traveled to the city.

With the information provided by the victims' families, identities of 35 victims had been confirmed, of whom nine were students, 13 were workers, 10 were migrant workers, one was a private businessperson and two were drivers. There were 24 men and 11 women.

Of the three injured people, two men and one woman remain in a stable condition.

A compensation plan for the victims has been organized and some 10 million yuan ($1.57 million) had been prepared by Inner Mongolia, Liang said.

Henan province was also preparing money for the compensation.

The Public Security Department of Inner Mongolia issued an emergency notice on Wednesday requiring its traffic police to enhance their checks and stop all buses between 2 am and 5 am when the drivers are required to rest in accordance of traffic law.

Zhang Zhuting, professor with Management College of Ministry of Transport, suggested that the supervision and management for vehicles carrying hazardous chemicals should be strengthened.

[email protected]