Rescuers in north-east China are trying to reach four miners trapped deep below ground after a massive gas explosion killed 111 people.

Twenty-four miners have been rescued after the blast in the town of Jixi in Heilongjiang province on Thursday morning. They are now in hospital, although none are said to be in a serious condition.

It has been an anxious wait for the miners' families

After the explosion, China's state coal mine safety bureau ordered an immediate halt to production at 10 mines in the town, which suffered two other mine blasts in April.

A BBC correspondent in Beijing, Rupert Wingfield-Hayes, says that anywhere else in the world, Thursday's blast would have been a shocking event, but in China it is just another statistic.

China has the most dangerous coal mining industry in the world, and despite efforts to improve safety, about 5,000 miners died in accidents last year.

Rescue operation

"We know where the four missing people are and we're trying very hard to rescue them," said Zhao Tiechui, deputy director of the China's Work Safety Administration.

According to the official Xinhua news agency, 60 bodies of those killed have been recovered.

The mines in Jixi have been closed down so that they can be inspected and the cause of the blast determined.

But our correspondent says that such investigations do little to get to the root of the problem with China's coal mines.

Chronic under-investment

Decades of under-investment have left China's mines decrepit.

Few mines have modern ventilation systems to extract the volatile coal gases that build up in the underground shafts and tunnels. A spark is all that is needed to set off a huge explosion.

Nearly 1,000 people were killed in just the first three months of this year and there is reported to be growing public outrage in the country at the stream of deaths.

China announced in April that it will close 8,000 small coal mines as part of efforts to streamline and regulate the industry.

But mines which are shut are often then re-opened with the support of local authorities, anxious for their profits.