The explosion occurred early on Friday at the Xinmin coal mine in northern Linxian county, and rescue operations were still underway, Xinhua reported. It was unclear how many miners were working underground at the time of the blast which, Xinhua said, initial investigations showed could have been caused by explosives such as dynamite.
The county-owned mine has an annual production capacity of 90,000 tonnes.
The accident comes after 16 miners, trapped at another mine for 14 hours by a mudslide, used spades and other tools to tunnel their way to safety as oxygen supplies dwindled.
The miners were forced to dig their eight meter (26 feet) tunnel after an estimated 1.4 million cubic meters (49 million cubic feet) of mud blocked the entrance to the mine in north-west Gansu province on Wednesday. Coal mines in China, which relies on coal for more than 70 percent of its power needs, are regarded as the most dangerous in the world.
Almost 6,000 workers were killed in the country's industry last year -- a rate of about 16 fatalities each day -- according to official figures.
Labour rights groups say the real number of mining deaths could be as high as 20,000 each year, with the official tally lower because local government officials and mine owners often cover up accidents.

Copyright AFP (Agence France-Presse), 2006