Last week a gas blast ripped through the Qifenggouxi coal mine in the north-west Shaanxi Province. At the time of the accident the mine was supposed to have suspended production due to ventilation problems.

It took four days for official agencies to find out about the blast as the mine tried to settle it privately by paying 2.54 million yuan ($US307,000) in compensation to the victims' families, a local production safety department told official news agency Xinhua.

Police had detained the coal mine manager, safety deputies and two workers in charge of gas inspections and safe-production inspections, Xinhua said.

China is the world's most dangerous mining country, accounting for 7000 fatalities annually in its coal mines.