This article is more than 9 years old

This article is more than 9 years old

An explosion in a Chinese coal mine has killed 21 miners in central Henan province, state media reported.

The accident occurred at 6am local time in a pit owned by Pingyu Coal and Electric based in Yuzhou city and rescue operations were under way, the Xinhua news agency said.

Rescuers have located 16 trapped miners but must clear tonnes of coal dust from the mine shaft to reach them, Xinhua cited a rescue spokesman as saying. It wasn't clear if the miners were alive or how far underground they were trapped.

The blast happened as workers were drilling a hole to release pressure from a gas buildup to decrease the risk of explosions, according to safety officials.

The more than 70 rescuers on the scene faced excessive gas levels and the risk of falling coal which had been loosened by the blast, according to China Central Television (CCT).

The blast unleashed more than 2,500 tonnes of coal dust, an engineer for one of the mine's parent companies, Du Bo, told Xinhua. The report said ventilation has resumed in the mining pit but gas levels remain high.

The gas level inside the mine was 40%, far higher than the normal level of near 1%, CCT reported. The type of gas wasn't specified, but methane is a common cause of mine blasts, and coal dust is explosive.

The bodies of all but one of the 21 dead miners had been retrieved, the report said.

State media said another gas blast at the same mine two years ago killed 23 people.

The explosion comes in the wake of Chile's dramatic rescue of 33 miners trapped for more than two months underground. China's propaganda and mine officials are likely to face pressure to be just as open about the progress of its rescue efforts.

China's mines are the deadliest in the world, due to lax safety standards and a rush to feed demand from a robust economy. More than 2,600 people died in coal mine accidents last year.

China had 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.

Mining fatalities had decreased in recent years as China closed many illegal mines, but deaths increased in the first half of this year. At least 515 people have been killed nationwide in coal mines alone.

An unknown number of illegal mines still exist to profit from the fast-growing economy's huge appetite for power. China's economy remains reliant on coal for about two-thirds of its energy needs.