A total of 86 miners were underground when the leak occurred on Thursday, Xinhua news agency said. Fifty-two were rescued, but one died later in hospital.

The cause of the gas leak was still under investigation.

China has the world's deadliest coal industry. Accidents in its mines killed 3,069 in the first 10 months of this year, a drop of 19 percent over the same period in 2006, state media say.