Nepal has resumed search and rescue work after a brief weather-related suspension as authorities search for nearly 3000 missing people following a devastating flood that killed hundreds and tore through a region bordering Tibet.
The impoverished Himalayan nation of 30 million people has called for specialist foreign assistance and its finance minister told Reuters it would need about $US4 billion ($A5.6 billion) to $US5 billion ($A7 billion) to rebuild.
Triggered by a glacier collapse, a torrent of rock, ice, mud and debris hurtled through mountain river systems on Wednesday, killing at least 669 people in Nepal and seven in China's Tibet. It swept away buildings, bridges and power stations.
Nearly 3000 people remain missing, including about 2426 in Nepal and 554 in Tibet's Gyirong County, among them at least 540 foreigners, including 42 Australians.
Search and rescue operations resumed in the afternoon after being temporarily halted because of rain and fog, a police officer in hard-hit Rasuwa district said.
"Helicopters are flying and the operation resumed following some improvement in weather," he said, on condition of anonymity as he was not authorised to speak to the media.
On Friday, authorities also suspended rescue work when a lake, formed across the Nepal-China border after the flood, began overflowing into Nepal's Lhende Khola and Trishuli rivers.
By Saturday, the risk had eased and parts of the lake bed were visible, Chinese authorities and state broadcaster CCTV said. Satellite images suggested water was slowly draining from the lake, gradually reducing its size, CCTV reported.
The lake is one of two upstream of the flood zone being monitored by Nepal. Flood risks will persist until both have fully drained, an official warned.
Three days after the disaster, authorities said some bodies being recovered had decomposed beyond recognition. They would be buried after legal formalities because of health risks and a fear of disease outbreaks.
"DNA samples will be collected, and the bodies will be buried in an open space," the Chitwan district administration said in a notice.
In Kathmandu, families of missing people gathered outside Maharajgunj Medical Campus, where some bodies had been taken. Many tried to identify relatives from photographs of the bodies displayed on gates and boundary walls.
In Malaysia, families of 91 citizens listed as "uncontactable" across Tibet and Nepal also waited for news.
Manivannan Rethinam, a representative for some of them, urged the foreign ministry to establish a communication channel for faster updates, saying the lack of information was "profoundly painful" for relatives awaiting news.
Malaysia's foreign ministry said search and rescue and verification efforts were continuing. India's Ministry of External Affairs said 275 Indian nationals were missing.
Survivors also face the daunting task of rebuilding their lives.
Nepal's Finance Minister Swarnim Wagle told Reuters the government's initial estimate was that rebuilding would cost between $US4 billion ($A5.6 billion) and $US5 billion ($A7 billion).
"This is just an estimate. Loss and damage is being assessed," he said.
Foreign Minister Shisir Khanal said Nepal required specialist assistance to rescue people trapped in tunnels; restore transport and communication lines where bridges had been destroyed; identify bodies; conduct DNA testing; and store bodies for longer periods.
A team of Indian tunnel experts arrived in Nepal on Saturday, he said, while China's Xinhua news agency reported Beijing had dispatched five tunnel experts to support rescue efforts, with four more due to join them.
India has already sent three flights carrying 60 tonnes of relief supplies, including blankets, medicines, and food.
It has also offered disaster-response personnel, prefabricated bridges and technical teams to help restore connectivity, the foreign ministry said.
Chinese authorities are also racing to trace more than 500 people still missing after the flood.
