The death toll from devastating flash floods triggered by a glacier collapse in Nepal has risen to 579, with 1,924 people still missing, as rescuers race to find survivors amid fears of further flooding in the Himalayan region.

The disaster, which struck northern Nepal and adjoining Tibet on Wednesday, has affected more than 90,000 people, destroyed roads, bridges and other critical infrastructure, and left hundreds of foreign tourists and pilgrims unaccounted for.

Reuters reported that rescue operations resumed on Friday after being briefly suspended over fears that a lake formed by flood debris could burst its banks and unleash another torrent of water and mud.

Nepalese authorities said the threat had eased sufficiently for search and rescue teams to return to the affected areas, although two upstream barrier lakes were still being monitored for possible flooding.

The flash flood was triggered after a glacier collapse sent huge volumes of rock, ice, mud and debris into Himalayan river systems, sweeping through villages and destroying homes, roads, bridges and power installations.