KATHMANDU: Nepali rescuers seeking to reach hydropower workers believed trapped in tunnels swamped by flood debris resumed work Sunday after rain and rising river waters hampered efforts.
Rescue operations entered their fifth day since the floods, as teams battled difficult conditions at the disaster sites.
Nepal's government says more than 100 workers may still be alive and trapped inside multiple tunnels at hydropower projects, with key rescue efforts focused on the Trishuli 3A and 3B sites.
They are among 933 hydropower workers missing since a wall of mud and debris swept down on Wednesday morning, according to the National Disaster Risk Reduction and Management Authority.
At Trishuli 3A, army rescue teams using drills broke through Saturday evening into the upper part of a mud-swamped tunnel, and began pumping air and sending in a camera.
But overnight rain and rising river waters hampered efforts early Sunday, filling the excavation area with water before conditions eased.
"As the floodwaters have receded, the team has resumed efforts to locate the tunnel entrance using drilling machines, excavators, hydraulic cutters, and other equipment," the Nepal Army said in a statement on Sunday.
Photographs shared by the disaster office showed workers wading through churned mud and navigating vast boulders left by the floods.
Nepal's prime minister's office said teams faced "difficult conditions" but were "making tireless efforts to search for and rescue those who may be trapped."
The rescue teams are using advanced search cameras and specialised monitors, it added.
The US Geological Survey said the disaster on the China-Nepal border was caused by a glacial collapse.
Specialised Indian and Chinese tunnel-rescue teams have also joined the efforts.
Nepal's expert mountain rescue teams -- who regularly aid climbers on the world's highest peaks, including Everest -- are also joining the search for missing people at another damaged hydropower site.
The Nepal Electricity Authority said 11 hydropower stations and one solar power station had stopped operating, with a combined capacity of 431.1 megawatts.
That represents about 10 percent of Nepal's installed electricity generation capacity, according to the authority.
Another 15 power projects under construction, with a combined planned capacity of 470 megawatts, have also been damaged.