The frequency for last year was 0.73 cases per day, said an official with SAWS, adding that the number of serious accidents in May causing three to nine deaths was up 30.3 percent on the previous year.

The serious situation deserves high vigilance, said Li Yizhong, director of SAWS at a meeting held on Tuesday.

If no firm measures are taken, it would be hard to avoid particularly severe cases in the future as the number of accidents is still on the rise, said Li.

While reporting recent coal mine safety work on Tuesday, Zhao Tiechui, director of the State Administration of Coal Mine Safety, said that township and countryside coal mines are having a higher ratio in the number of accidents in May.

Unlicensed coal mining is still a prominent problem and gas and flooding cases have occurred frequently, said Zhao.

Both of the two directors urged more efforts to close unsafe coal mines and launch alarm systems against flooding accidents.

The latest coal mine flooding in Zuoyun County of North China's Shanxi Province has left 56 miners trapped and feared dead after more than two weeks.