An accident at a coal mine in China trapped at least 43 workers underground on Thursday, state media and officials said, the latest in a string of incidents to hit the country's vast mining industry.

Rescuers have rushed to the scene of the accident, which occurred early Thursday in the southwestern province of Yunnan, the official Xinhua news agency said.

The cause of the accident was not immediately clear. Xinhua said there had been a gas leak while a local mine safety official told AFP the mine may have been hit by a "coal and gas outburst."

An outburst is a sudden and violent ejection of coal, gas and rock from a coal face in an underground mine, which can cause serious injuries as well as damage machinery.

It was not clear how many miners were in the privately run Sizhuang Coal Mine at the time of the accident, which comes days after a rock blast in a coal mine in the central province of Henan trapped dozens of workers underground.

Most were eventually pulled out after a 40-hour rescue operation, though 10 were killed.

Coal mine accidents are common in China, where work safety is often neglected by bosses seeking a quick profit.

Last year, 2,433 people died in coal mining accidents in the country, according to official statistics -- a rate of more than six workers per day.

Labour rights groups, however, say the actual death toll is likely to be much higher, partly due to under-reporting of accidents as mine bosses seek to limit their economic losses and avoid punishment.

China's rapid economic growth has caused demand for energy, including coal, to surge.

The Asian nation is the world's leading consumer of coal, relying on it for 70 percent of its growing energy needs.

Over the past eight years it has on average built one coal-fired power station a week. And with the arrival of winter, mines are operating at full capacity.

Fatalities at Chinese coal mines peaked in 2002 when 6,995 deaths were recorded, sparking efforts by the government to boost safety standards.

In its latest campaign, the government last year issued a policy that required six kinds of safety systems -- including rescue facilities -- to be installed in all coal mines within three years.

But accidents still occur on a regular basis. Last month, a gas explosion at a state-owned coal mine in the central province of Hunan left 29 miners dead.

Earlier in October, blasts at mines in the southwestern city of Chongqing and the northern province of Shaanxi killed 13 and 11 miners respectively.