Sixteen people were trapped in a flooded coal mine in central China on Thursday, state media reported, the latest accident to occur in an industry that claims thousands of lives each year.
The mine in Hunan province flooded Wednesday evening and by late Thursday morning none of the 16 trapped miners had been rescued, Xinhua news agency reported.
Rescue work was ongoing, it added. The cause of the flood was not immediately known.
Accidents in China's mines occur frequently.
But increased safety standards have appeared effective with the latest figures showing that 1,973 people died in coal mining accidents in 2011, a 19 percent fall compared with a year earlier, according to government figures.
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 biggest consumer of coal, relying on the fossil fuel for 70 percent of its growing energy needs.