The state-run Xinhua news agency confirmed the accident at the Huangling Mining Co Ltd's No 1 coal mine on Wednesday, but did not reveal the cause.

Some 85 miners had being working underground when the blast occurred on Tuesday. All but 20 were rescued immediately, though half a dozen had to be hospitalised.

Two rescuers were among the dead but Xinhua did not say how they were killed. 
The state-owned mine went into operation in 2001.
China's mining industry is the world's biggest and most dangerous, with thousands of people killed in explosions, floods and other serious accidents every year.