A coal mine owner who allegedly covered up a deadly mine blast in Northeast China has reportedly confessed that an illegally-acquired cremation certificate was used to conceal the cause of the miners' deaths.

Rescuers descend to look for the last miner trapped underground in Guifa coal mine in Didao district, Jixi city, Heilongjiang province, on Tuesday. The mine owner allegedly initially tried to cover up the gas blast that happened on April 26, killing nine miners.

An unidentified local police officer allegedly provided Gao Zhenhe, the mine owner, with a blank certificate bearing the seal of the forensic science and technology department of the local public security bureau to help him have the miners' bodies cremated without stating the real cause of their deaths, Xinhua News Agency reported on Tuesday, quoting a member of the team investigating the accident.

Nine miners were killed in a gas explosion at the privately run Guifa coal mine in Didao district, Jixi city, Heilongjiang province, on April 26.

The cremation certificate had been obtained from a local police officer, Gao said, after turning himself in to the local police on Sunday.

The cover-up was discovered on April 30 when investigators, acting on rumors of an accident at the mine, discovered a hidden tunnel where miners had been working when the gas blast occurred. Before the accident, the mine had been ordered to stop operations because its production license had expired.

Gao had allegedly paid the miners' families hush money. He paid Liu Guojun, the younger brother of Liu Guoshan who was killed in the accident, 1 million yuan ($154,000) at a crematorium to prevent the family from informing local authorities, said a statement published on the official website of the Jixi government.

But Gao failed to reach a similar deal with the family of another dead miner, whose body had not been recovered.

"Rescuers are trying to recover the body of the last miner trapped underground," said Hou Yuxi, a senior official with the Heilongjiang Administration of Coal Mine Safety.