Eleven of the 16 miners trapped in a flooded colliery pit in central China are alive and in the process of being rescued, state media reported early Sunday.

The miners were trapped in the pit in Leiyang city in Hunan Province on Wednesday but the accident was not reported to the government until the following day, delaying rescue efforts by 12 hours, Xinhua news agency said.

The mine's owner, Liu Yaping, is now under police custody, the report added.

Medical personnel have gone into the pit carrying stretchers and first-aid material, rescuers told the news agency.

The miners would be extracted from the pit in three groups and rushed to hospital for treatment, they said.

Six teams of 90 members and more than 1,000 people were at the scene to help with the operation.

Accidents in China's mines occur frequently.

Tighter safety standards appear to have been effective according to the latest official figures, which say that 1,973 people died in coal mining accidents in 2011, down 19 percent on the previous year.

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.