Hopes were fading Sunday that Chinese search and rescue teams would find survivors, two days after a huge landslide crashed down a Tibetan mountain and buried more than 80 mine workers.

Around 3,500 rescuers were searching for survivors and 300 pieces of large machinery had been mobilised, state media reported Sunday, with workers battling snow and altitude sickness.

Fifteen bodies were recovered Sunday, bringing the total to 17 after two were found Saturday, the Xinhua news agency said. That would leave 66 miners unaccounted for under two million cubic metres of earth.

The disaster struck when a huge section of land tumbled onto a mine workers' camp in Maizhokunggar county, east of the Tibetan capital Lhasa, at 6:00 am on Friday (2200 GMT Thursday). The first body was found at 5.35 pm Saturday.

Yang Dongliang, head of the State Administration of Work Safety, said an inquiry into the landslide's cause had started with the arrival of experts from the Ministry of Land and Resources.

Xinhua said many rescuers had dug with their "bare hands" because damage to narrow local roads had kept much of the large-scale rescue machinery from reaching the site.

Mountainous regions of Tibet are prone to landslides, which can be exacerbated by heavy mining activity, and the chance of further landslides heightened safety concerns.

"There are cracks on the mountaintop and secondary disasters are possible," said Jiang Yi, a police officer taking part in the rescue, according to Xinhua.

In addition to rescuers and machinery, a total of 10 sniffer dogs and 20 life detectors had been mobilised, Xinhua said.

The disaster zone is 4,600 metres (15,000 feet) above sea level and altitude sickness was a challenge, with more medical personnel being sent to the scene.

"We have treated rescuers who suffered altitude sickness or a fever due to the snowy weather," Li Suzhi, president of the General Hospital of Tibetan Military Command, was quoted by the news agency as saying.

The victims worked for a subsidiary of the China National Gold Group Corporation, a state-owned company and the nation's biggest gold miner by output.

According to the Chinese government, the mine produces copper as well as other metals.

Almost all those buried were Han Chinese, the national ethnic majority, with only two ethnic Tibetans, Xinhua said Saturday. Most were migrant workers from the provinces of Yunnan, Guizhou and Sichuan.

One of those trapped, 19-year-old He Yuan from Guizhou, recently went to the mine to earn money to support his family including his sick father. He planned to marry his girlfriend when he turned 22, Xinhua reported.

"He Yuan is the only son of my sister," it quoted one of his uncles, Yuan Song, as saying. "How can she survive without him?"

Newly-installed president Xi Jinping, who returned Sunday from Russia and Africa, and new Premier Li Keqiang ordered "top efforts" to rescue victims.

In recent years China has discovered huge mineral resources in Tibet, including tens of millions of tonnes of copper, lead and zinc, and billions of tonnes of iron ore.

The Tibetan landslide came on the same day as a gas blast in a northeast China coal mine killed 28 people. State media said 13 others were rescued after the accident at Babao Coal Mine in the city of Baishan in Jilin province.