According to the Xinhua News Agency, the incident happened on Thursday night at the Qianqiu coal mine where 75 miners were working in the shaft of the colliery.

Some 15 miners managed to escape, leaving 60 trapped

Early details from the incident confirmed four men died.

The death toll then rose to eight on Friday after four more victims were recovered, said the China Daily news service.

The rock blast was believed to occur about 480m into the 760m deep shaft.

China Daily said the search team contacted the survivors approximately 550m into the shaft and brought the miners to the surface after unclogging the shaft.

Local media reports said the rock burst occurred approximately half an hour after a 2.9 magnitude earthquake struck to the east of Sanmenxia.

The Qianqiu coal mine has an annual production capacity of 2.1 million tonnes and belongs to state-owned coal enterprise, Yima Coal Group.

China’s coal mines remain the most dangerous in the world, although recent government efforts to close smaller and illegal mines have seen a slight improvement in safety standards.

According to figures obtained from the State Administration of Coal Mine Safety, 2433 miners were killed in coal mine accidents in China in 2010, while Xinhua news service said there had been 512 coal mine incidents in China this year, as of June 2011.