|Rescuers have located the trapped miners but must clear tonnes of coal dust to reach them [Reuters]
At least 21 miners have been killed, with 16 more trapped underground, in a coal mine in China's central Henan province after an accident, state media has reported.
The accident happened on Saturday when the mine in the city of Yuzhou was hit by a "gas outburst", Xinhua news agency said.
Rescuers have located the trapped miners about 50 to 80 metres below the pit entrance but must clear tonnes of coal dust from the mine shaft to reach them, the agency cited a rescue spokesman as saying.
"The thick dust in the shaft is hampering the rescue. We must clear the dust first," Du Bo, an engineer for one of the mine's parent companies, was quoted by Xinhua as saying.
He said more than 2,500 tonnes of coal dust had smothered the pit after the gas leak, suffocating most of the victims.
More than 70 rescuers working in shifts at the scene also must clear chunks of coal loosened by the blast that fell into the shaft, Xinhua said.
The gas that caused the blast was not specified, but methane is a common cause of mine blasts, and coal dust is also explosive.
The Henan mine is jointly owned by China Power Investment Corp - a major state-owned power producer - and another firm, Xinhua news agency said.
The China blast comes shortly after the world was riveted by Chile's dramatic rescue of 33 trapped miners after they spent more than two months underground.
Inefficiency and corruption
The incident is the latest mishap to strike China's notoriously dangerous mining sector.
Last year, some 2,630 Chinese miners were killed, according to official statistics, but independent labour groups say the true figure is likely to be much higher as many accidents are believed to be covered up.
The high fatality rate is generally blamed on inefficiency and corruption in the sector, with coal mining being particularly accident-prone.
Internet chatrooms - a rare platform for relatively open debate in Communist-controlled China - slammed the country's safety record after the Chilean rescues.
Some state media editorials said China should learn from the better training and safety systems of the Chilean miners.
Many Chinese miners are ill-trained migrant workers toiling in pits where even basic safety is ignored.
The government has repeatedly vowed to shut dangerous mines and strengthen safety, but accidents continue with regularity as mine operators work to pump out the coal on which China relies for about 70 per cent of its energy.
China celebrated its own stunning mine rescue earlier this year, when 115 miners were pulled from a flooded mine in the northern province of Shanxi after more than a week underground.
The miners survived by eating sawdust, tree bark, paper and even coal. Some strapped themselves to the walls of the shafts with their belts to avoid drowning while they slept.