More than 400 people in Tibet trapped by a deadly earthquake in the foothills of the Himalayas have been rescued, Chinese officials said on Wednesday, but an unknown number remained unaccounted for in severe cold weather.

The epicentre of Tuesday's magnitude 6.8 quake, one of the region's most powerful tremors in recent years, was located in Tingri in China's Tibet, about 80 km north of Mount Everest, the world's highest mountain. It also shook buildings in neighbouring Nepal, Bhutan and India.

Reuters reported that 24 hours after the temblor struck, those trapped under rubble would have endured a night in sub-zero temperatures, adding to the pressure on rescuers looking for survivors in an area the size of Cambodia.

Temperatures in the high-altitude region dropped as low as minus 18 degrees Celsius overnight.

People trapped or those without shelter are at risk of rapid hypothermia and may only be able to live for five to 10 hours even if uninjured, experts say.

At least 126 people were known to have been killed and 188 injured on the Tibetan side, state broadcaster CCTV reported.

No deaths have been reported in Nepal or elsewhere.

Chinese authorities have yet to announce how many people are still missing.

In Nepal, an official told Reuters the quake destroyed a school building in a village near Mount Everest, which straddles the Nepali-Tibetan border, but no one was inside at the time.

Jost Kobusch, a German climber, said he was just above the Everest base camp on the Nepali side when the quake struck.

"I'm climbing Everest in the winter by myself and...looks like basically I'm the only mountaineer there, in the base camp there's nobody"

His tent shook violently and he said he saw several avalanches crash down, although he was unscathed.

"I'm climbing Everest in the winter by myself and...looks like basically I'm the only mountaineer there, in the base camp there's nobody," he told Reuters in a video call.

His expedition organising company, Satori Adventure, said Kobusch had left the base camp and was descending to Namche Bazaar on Wednesday on the way to Kathmandu.

An initial survey showed 3,609 homes had been destroyed in Tibet's Shigatse region, home to 800,000 people, state media reported late on Tuesday, citing local officials.

Over 1,800 emergency rescue personnel and 1,600 soldiers had been dispatched to the region.

More than 500 aftershocks with magnitudes of up to 4.4 had followed the quake as of 8 a.m. on Wednesday, the China Earthquake Networks Centre said.

In 2008, an 8.0 magnitude earthquake hit Sichuan's Chengdu, claiming the lives of at least 70,000 people, the deadliest quake to hit China since the 1976 Tangshan quake that killed at least 242,000 people.

A magnitude 6.8 earthquake, rocked the northern foothills of the Himalayas near one of Tibet's holiest cities on Tuesday, Chinese authorities said, killing at least 53 people and shaking buildings in neighbouring Nepal, Bhutan and India.

The quake hit at 9:05 a.m. Tibet time, with its epicentre located in Tingri, a rural Chinese county known as the northern gateway to the Everest region, at a depth of 10 km, according to the China Earthquake Networks Centre.

The U.S. Geological Service put the quake's magnitude at 7.1.

At least 53 people had been killed and 62 injured on the Tibetan side, China's state-run news agency Xinhua reported.

Southwestern parts of China, Nepal and northern India are frequently hit by earthquakes caused by the collision of the Indian and Eurasian tectonic plates.

A magnitude 7.8 tremor struck near Kathmandu in 2015, killing about 9,000 people and injuring thousands in Nepal's worst ever earthquake.

Among the dead were at least 18 people killed at the Mount Everest base camp when it was smashed by an avalanche.

Tuesday's epicentre was around 80 km north of Everest, the world's highest mountain and a popular destination for climbers and trekkers.

Winter is not a popular season for climbers and hikers in Nepal, with a German climber the lone mountaineer with a permit to climb Mount Everest.

He had already left the base camp after failing to reach the summit, Lilathar Awasthi, a Department of Tourism official, said.

Nepal’s National Disaster Risk Reduction and Management Authority (NDRRMA) said the tremors were felt in seven hill districts bordering Tibet.

"So far we have not received any information of any loss of life and property," NDRRMA spokesman Dizan Bhattarai told Reuters.

"We have mobilised police, security forces and local authorities to collect information," he said.

Many villages in the Nepalese border area, which are sparsely populated, are remote and can only be reached by foot.

The impact of the quake was felt across the Shigatse region of Tibet, home to 800,000 people. The region is administered by Shigatse city, the traditional seat of the Panchen Lama, one of the most important figures in Tibetan Buddhism.

Chinese President Xi Jinping said all-out search and rescue efforts should be carried out to minimise casualties, properly resettle the affected people, and ensure a safe and warm winter.

Villages in Tingri, where the average elevation is around 4,000-5,000 metres, reported strong shaking during the quake, which was followed by dozens of aftershocks with magnitudes of up to 4.4.

Crumbled shop fronts could be seen in a video on social media showing the aftermath from the town of Lhatse, with debris spilling out onto the road.

Iran's disputed uranium enrichment drive is nearing a point of no return and European partners to a moribund 2015 nuclear deal with Tehran should consider reimposing sanctions if there is no progress with Tehran, France's president said on Monday.

Addressing an annual conference with French ambassadors to outline foreign policy objectives in 2025, President Emmanuel Macron described Iran as the main "strategic and security challenge" for France and Europe, Reuters reported.

"The acceleration of the nuclear programme leads us nearly to the point of no return," Macron said.

Iran says it is enriching uranium for peaceful purposes and has stepped up the programme since U.S. President-elect Donald Trump pulled Washington out of the 2015 deal during his first term of office and restored tough U.S. sanctions on Tehran.

European powers France, Germany and Britain said last month Iran’s actions had further hollowed out the deal and would heighten its stockpile of high-enriched uranium without a "credible civilian justification".

The head of the U.N. nuclear watchdog said in December that the Islamic Republic was "dramatically" accelerating enrichment close to the roughly 90% level that is bomb-grade, read the report.

The three European powers were co-signatories to the 2015 deal in which Iran agreed to curb enrichment, seen by the West as a disguised effort to develop nuclear-weapons capability, in return for a lifting of international sanctions.

French, German and British diplomats are set to hold a follow-up meeting with Iranian counterparts on Jan. 13 after one last month held to discuss the possibility of serious negotiations in coming months to defuse tensions with Tehran with Trump due to return to the White House on Jan. 20.

"In the coming months we will have to ask ourselves whether to use ... the mechanism to restore sanctions," Macron said, referring to October 2025 when the 2015 accord formally expires.

Macron said Iran's ballistic missiles and support for Russia also posed threats to Europe and this would become one of the main dossiers to be addressed in diplomacy with Trump after he took office, Reuters reported.