Nine miners were killed Wednesday by a sudden outburst of gas and coal at a coal mine in southwest China's Yunnan Province, local authorities said.

The accident occurred at the Goutou coal mine in Weixin County, Zhaotong City, at around 11 a.m. Wednesday, Weixin publicity officials said late Wednesday afternoon.

Rescuers have recovered the bodies of the nine miners. The cause of the accident is under investigation.

No other details were immediately available.

China relies heavily on coal to fuel its fast growing economy. Accidents are frequent in small mines with inadequate safety measures.

On June 21, an underground explosion rocked the Xingdong No. 2 Mine in central China's Henan Province, trapping 75 miners. Forty-nine of them died.

The accident was caused by illegal operations, the state work safety watchdog said.