At least 15 miners were killed in two mine floods in China over the weekend, as rescuers frantically pumped mining shafts in search of seven still missing in the accidents, state press said Sunday.

The death toll in a flood that occurred early Friday at the illegally operating Shanfu coal mine in north China's Shanxi province rose to 10, Xinhua news agency said. One miner remains missing and rescue operations continue.

Investigators have discovered that the mine was operating with an expired production license, Xinhua added. The mine owner, manager and 19 others have been taken into police custody as part of the investigation.

In a separate incident, five workers were confirmed dead and six others missing when the Yulongyuantong coal mine in central China's Henan province flooded on Saturday, Xinhua said in a separate report.

It said 53 miners were in the shaft at the time of the flood, and 42 managed to escape.

Latest figures show 1,973 people died in coal mining accidents in China in 2011, a 19 percent fall in fatalities compared to a year earlier, the government reported.

Labour rights groups, however, say the actual death toll is likely to be much higher, partly due to under-reporting of accidents as mine bosses seek to limit their economic losses and avoid punishment.

China is the world's leading consumer of coal, relying on the fossil fuel for 70 percent of its growing energy needs.