Tibetan rescue teams are searching for 83 miners buried in a landslide in Maizhokunggar county on Friday.
The chances of finding survivors at the mine near the Tibetan capital, Lhasa, were slim, Chinese media quoted rescuers as saying.
The miners’ camp, at an altitude of 15,000 ft, 45 miles east of Lhasa, was destroyed by thousands of tonnes of rock.
Rescuers have been hampered by freezing weather, altitude sickness and risks of further landslides.
Xinhua news agency said that as of 10:00 local time no survivors had been found.
“The miners’ survival chances were slim due to the scale of the landslide,” it quoted one rescue worker as saying.
Some 2,000 police, firefighters and doctors have been sent to the disaster site, setting up temporary accommodation at a safe distance. About 200 bulldozers have been deployed to shift rock.
Xinhua said cracks on nearby mountains suggested there could be further land slips.
“Temperatures as low as -3C have affected the sniffer dogs’ sense of smell,” it added.
More than 300,000 cubic meters of debris had been removed by midday on Saturday.
The Maizhokunggar mine, which produces copper, as well as some silver and gold, is operated by a subsidiary of state-owned China National Gold Group, China’s biggest gold producer.
Chinese President Xi Jinping is said to have ordered authorities to “spare no efforts” in the rescue operation.
Most of the workers were ethnic Han Chinese from Yunnan, Guizhou and Sichuan provinces, with two reported to be ethnic Tibetans.
Police said the area that collapsed was up to 1.5 sq miles.
Chinese officials believe the Tibetan plateau has huge resources, including millions of tonnes of copper, lead, zinc and iron ore.
Critics claim that Beijing’s interests are driven by a desire to exploit the region’s rich mineral wealth.
The government argues its investment brings modernization and better living standards for local Tibetans.
The landslip came on the same day as a gas explosion at a coal mine in north-eastern Jilin province.
Some 28 people were killed at the Babao mine in the city of Baishan.
Another 13 miners were rescued after the explosion.