A massive landslide engulfed a gold mining area in mountainous Tibet, burying 83 workers believed to have been asleep early Friday morning, Chinese state media said.

About 2 million cubic metres of mud, rock and debris swept through the area as the workers were resting and covered an area measuring around 4 square kilometres, China Central Television said.

The official Xinhua News Agency said the workers in Lhasa's Maizhokunggar county worked for a subsidiary of the China National Gold Group Corp., a state-owned enterprise and the country's largest gold producer.

The disaster is likely to inflame critics of Chinese rule in Tibet who say Beijing's interests are driven by the region's mineral wealth and strategic position and come at the expense of the region's delicate ecosystem and Tibetans' Buddhist culture and traditional way of life.

The reports said at least two of the buried workers were Tibetan while most of the workers were believed to be ethnic Han Chinese, a reflection of how such large projects often create an influx of the majority ethnic group into the region.

More than 1,000 police, firefighters, soldiers and medics have been deployed to the site, about 70 kilometres east of Lhasa, the regional capital. They conducted searches armed with devices to detect signs of life and accompanied by sniffer dogs, reports said.

Around 30 excavators were also digging away at the site late Friday as temperatures fell to just below freezing.

Caused by 'natural disaster'

The reports said the landslide was caused by a "natural disaster" but did not provide specifics. It was unclear why the first news reports of the landslide came out several hours after it occurred.

China's recently appointed President Xi Jinping and Premier Li Keqiang ordered authorities to "spare no efforts" in their rescue work, Xinhua said.

County officials reached by phone confirmed the landslide but had no further details, saying that information reaching the main office was limited due to poor cellphone coverage at the site. Calls to the company's general phone line rang unanswered.

Doctors at the local county hospital said they had been told to prepare to receive survivors but none had arrived. "We were ordered to make all efforts to receive the injured," said a doctor who gave only her surname, Ge, in the hospital's emergency section.

Ge said the hospital transferred some of its patients to other facilities to increase the number of beds available and that 16 doctors were on duty.

The Chinese government has been encouraging development of mining and other industries in long-isolated Tibet as a way to promote its economic growth and raise living standards. The region has abundant deposits of copper, chromium, bauxite and other precious minerals and metals and is one of fast-growing China's last frontiers.

Tibet remains among China's poorest regions despite producing a large share of its minerals. A key source of anti-Chinese anger is complaints by local residents that they get little of the wealth extracted by government companies, most of which flows to distant Beijing.

In 2008, unhappiness with Chinese rule spilled over into deadly riots that engulfed Lhasa and an anti-government uprising that swept many Tibetan communities. To quell the unrest, Beijing poured security forces into Tibetan areas and has kept them there since, giving the western China region the feel of a military garrison and further alienating many Tibetans.

In recent years, more than 100 Tibetans have set themselves on fire to protest the stifling security presence and call for greater religious freedom.