Nepal's rescue teams, aided by Chinese and Indian experts, are racing to save more than 900 workers believed to be trapped underground at hydropower projects hit by devastating flash floods.
Nepali officials said on Monday that the focus was on reaching the workers in about a dozen hydropower project tunnels blocked by mud and rock debris.
An unprecedented deluge of ice, rock, mud and debris along the Nepal-Tibet border on Wednesday, caused by a glacier collapse, has killed 903 people, with 4,247 missing in Nepal, according to the country's disaster authority.
The flood also wreaked havoc across the border in China's Tibet region, where at least 16 people died and 546 are missing, Chinese authorities said.
Pictures and videos shared by rescue teams showed earth-moving equipment digging and shovelling mud and rocks under lights in the dark of night as workers watched. Soldiers used torchlights in a large pit they had created while searching for a way into one of the tunnels.
"A large amount of debris has been deposited and that is posing us a big challenge to open the tunnels," Nepal Army spokesperson Raja Ram Basnet said. "Our main focus is on opening the tunnels."
Hundreds of bodies, many unidentified, have been buried in shallow graves as they began decomposing in the humid weather after being swept down the mountains by the torrent.
At hospitals in the capital, Kathmandu, morgues have reached capacity and families are flocking to other facilities in hopes of finding missing loved ones.
In addition to the 933 missing hydropower workers, some 500 workers from the Truck and Container Association are also reported missing.
The Red Cross has estimated that more than 90,000 people are likely to have been affected by the disaster, which China has linked to the effects of climate change.
Prime Minister Balendra Shah described the flood as an "unprecedented and devastating natural disaster" and said it remained challenging to compile a complete assessment of the damage.
"Despite the adverse weather, difficult terrain and continuing risks, we are moving forward with determination to save the lives of our citizens," he said in a statement issued late on Sunday, adding that nearly 21,000 security personnel were involved in rescue operations alongside civilian workers and volunteers.
While accessibility has been restored on many roads and highways, approximately 40 kilometres of roads have been completely swept away, creating significant obstacles to delivering aid to affected communities.
China's state broadcaster reported that the government has mobilised more than 2,100 rescue workers and allocated at least 220 million yuan ($33 million) to support relief efforts. Equipment and supplies have been airdropped to frontline rescuers, while Chinese soldiers used life-detection equipment to search for the missing.
Beijing said 261 foreign nationals from 23 countries were unaccounted for in Tibet.
China has sent nine tunnel rescue experts to Nepal and shared satellite information with Nepali authorities.
Although Nepal has said it does not require foreign assistance for general search and rescue efforts, it has accepted help from neighbouring India and China for their expertise in tunnel rescue.
Rescue operations have been suspended several times since Friday due to bad weather and concerns that a lake formed across the Nepal-China border by the disaster could trigger new flooding after it began overflowing into Nepal's rivers.
Weather conditions improved on Monday and rescue work continued to pick up pace, said Narendra Pariyar, the district administrator of Rasuwa, one of the two hardest-hit districts.
