Six miners have died in a coal mine accident in northwest China's restive Xinjiang region, according to the country's official Xinhua news agency.

The accident happened on Tuesday evening at the Hongxing Coal Mine in Changji City, the report quoted the region's mine safety supervisory agency as saying. The cause was not immediately known.

Rescuers have discovered six bodies, and six injured miners have been rushed to hospital for treatment, a mining official told the agency.

The privately-owned mine has an annual production capacity of 90,000 tonnes, the report added.

Accidents in China's mines occur frequently. Last month, 53 rescuers sent in to recover five trapped miners at a colliery in southwest China had to be pulled to safety after they too became stuck underground.

However, tighter safety standards appear to have been effective according to the latest official figures, which say 1,973 people died in coal mining accidents in 2011, down 19 percent on the previous year.

China is the world's biggest consumer of coal, relying on the fossil fuel for 70 percent of its growing energy needs.

Xinjiang is home to around nine million Uighurs, a Turkic speaking, largely Muslim ethnic minority.

Many Uighurs accuse China's rulers of religious and political persecution, while complaining that their homeland is being inundated with the nation's dominant Han ethnic group.

China denies claims of repression, saying it has brought badly needed modernisation and economic development to the vast and landlocked region bordering Central Asia.