Water pipes used for rescue operation at Jindi Coal Mine in Jidong county. [Photo/Xinhua]

JIDONG, HEILONGJIANG- Rescuers said on Saturday they had found no sign of life four days after 13 miners were trapped under a flooded coal mine in northeast China's Heilongjiang Province.

Efforts to pump water out of the mine continued, though the prime time for rescue efforts had passed, according to Peng Jianxun, deputy head of the State Administration of Coal Mine Safety (SACMS).

Police have detained the boss of Jindi Coal Mine, a licensed private mine in Jidong county, who apparently tried to cover up the accident after the flood hit the mine on Tuesday afternoon.

The mine owner later confessed to the police that 24 people were underground when the accident happened, with 11 of them managing to escape.

The cause of the accident is still under investigation, and it is still unknown how many hours it would take to drain the mine.