The cause of the explosion is not known.

All of the victims died of carbon monoxide poisoning, Xinhua reported, citing an unidentified city official.

China's mines are among the most dangerous in the world, with safety standards often ignored in the quest for profits and the drive to meet a soaring demand for coal - the source of about 70 per cent of China's energy.

Nearly 3,800 lives were lost in Chinese mines last year from explosions, cave-ins and floods, down 20 per cent from the year before, according to official figures.