Rescue workers had earlier drilled holes in the hope of communicating with the missing miners, but no signs of life were detected.

Deadly mines

The mine is owned by Wuhai Energy Co. Ltd. whose parent company Shenhua Group Corp. Ltd. is one of China's major mining firms.

China's mining industry is the world's deadliest, with thousands of mines killed every year in tunnel collapses, underground explosions and other accidents.

Most incidents occur in smaller mines, or mines operating illegally after being shut down by authorities.

According to the latest official figures, more than 3,000 miners were killed in 2008 alone.

China's government has vowed to crackdown on work safety, but while laws exist on paper enforcement of regulations has often been lax.

In addition, China's huge appetite for energy combined with a ready supple of cheap migrant labour has meant many mine owners cut corners on safety in pursuit of a quick profit.