The efforts to search for the other miners are still going on, said sources from the rescue headquarters.

The blast occurred at 6:30 p.m. on Sunday at Miaojiang Coal Mine, in Chengqu District of Jincheng City, Shanxi Province, but the mine owner allegedly failed to report the accident to the emergency services, said sources with Shanxi Provincial Bureau of Work Safety.

On Tuesday afternoon, people close to the company reported the accident to the provincial bureau of work safety, which ordered Jincheng City Bureau of Work Safety to immediately investigate.

A team from the bureau on Tuesday confirmed the explosion after completing the investigation.

A rescue team arrived at the site at 8:40 p.m. to discover that the main shaft and the side passage were sealed off.

The rescuers unblocked the shaft and found that the miners had been working beyond the officially approved coal bed.

Police have arrested 11 people in connection with the coal mine gas explosion, including Wang Junjun, the owner of the Miaojiang Coal Mine, who allegedly attempted to conceal the incident.

Questioned by police early on Wednesday, Wang allegedly admitted there was a gas blast on Sunday and that 21 miners who were working underground at the time were trapped.

The Shanxi Office for Resources Integration had instructed the Miaojiang mine to merge with the nearby Gaojiang Coal Mine, with a combined production limit of 90,000 tons a year.

Instead of following the instruction, the operators of the Miaojiang mine organized production illegally and breached the approved stratum for coal production, which led to the accident, said a spokesman for Jincheng City government.

All coal mines in Jincheng, in the southeast of Shanxi, had been ordered to stop production and carry out safety evaluations since the blast.

"Coal mine operators should draw lessons from Sunday's explosion and ensure that safety measures be carried out to the letter," he said.

Provincial Communist Party and government leaders ordered the use of all possible resources in the rescue operation, and a thorough investigations into the exact number of the casualties, the cause of the accident and suspected cover-up attempts.

Vice Governor Jin Shanzhong on Wednesday led a group of expertsto Miaojiang Coal Mine to oversee the rescue efforts.

Miaojiang Coal Mine is not the first nor the last coal mine in delaying the reporting of an accident or in attempting a cover-up.

Police in northeast China have arrested the owner of a coal mine who allegedly tried to cover up a fire in which at least six miners were killed.

Xiang Fangshu, owner of the Dongfang No.1 Coal Mine in Dongliang Township of the Fuxin Mongolian Autonomous County, Liaoning Province, was detained on Wednesday, as investigation into the fire went deeper.

The fire broke out at about 3:40 p.m. on Sunday when 35 miners were working below ground. Six miners were suffocated by the fumes and 15 were injured.

Only 14 miners managed to escape unhurt from the mine.

The injured miners, mostly suffering from severe burns, are being treated in a local hospital.

Xiang allegedly attempted to handle the accident himself and failed to report it to local work safety authorities, but on Monday afternoon the disaster was reported by someone close to the company.

Xiang allegedly admitted the fire to a team that went to investigate.

In his government work report delivered to the just-concluded annual session of the National People's Congress, Chinese Premier Wen Jiabao reiterated that work safety should be tightened.

Critics say the attempted cover-ups in Shanxi and Liaoning on the same day are flagrant rejections of Premier Wen's words and proves that local government supervision is weak.

More should be done to improve its coal mining safety, as its sustained robust economic growth is driving up demands for coal, the biggest source of energy in China.