Although safety conditions have improved sharply in recent years, China's mining industry remains by far the world's deadliest, with accidents and blasts killing more than 2,600 miners last year.

Independent labour groups say the actual figure could be much higher as many accidents are covered up to avoid costly mine closures.

Zhao Tiechui, the head of the State Administration of Coal Mine Safety, said in February that China would need at least 10 years to "fundamentally improve" safety and reduce the frequency of such disasters.

"Awareness of safety and the rule of law is still low in some coal-rich areas and some coal enterprises," he said.

As part of its efforts to increase safety standards, the central government has imposed heavy fines and implemented region-wide mining shutdowns following serious accidents.

But such actions have resulted in the under-reporting of accidents as mine bosses seek to limit economic losses, labour rights groups say.