The death toll from a rain-triggered mudslide in north China's Shanxi Province rose to 151 as of Thursday afternoon, with 35 injured, the local rescue headquarters said.

The State Council, China's Cabinet, has set up an accident investigation team, including officials from the State Administration of Work Safety, Shanxi provincial government, Ministry of Supervision, Ministry of Land and Resources, and All China Federation of Trade Unions.

The team, headed by Wang Jun, the State Administration of Work Safety director, also invited the Supreme People's Procuratorate to assist in the investigation.

After a preliminary investigation, the team believed it was an "accident of grave responsibility" resulting from the illegal operation of an unlicensed ore mine.

"It is the most grave accident that involves the largest death toll so far this year," Wang said. "The rising accidents disclose local governments' poor supervision on work safety. Those responsible must be dealt with seriously."

Police have detained 13 people who were held accountable for the accident, including board chairman of the Xinta Mining Company, the mine manager, a vice manager and an accountant.