KATHMANDU — The United Nations launched an appeal for $50 million to aid more than 84,000 flood victims in Nepal on Sunday, as rescue and recovery operations accelerated a week after catastrophic flash floods struck the Nepal-Tibet border region.

Pieters Yahia, the UN's resident coordinator in Nepal, said survivors watched their lives transform in "one to two minutes."

Nepal's disaster authority reported 1,252 bodies recovered, with 4,216 people still missing. Chinese state media reported 21 deaths and more than 540 people unaccounted for on the Tibetan side. Officials fear the death toll will rise as recovery efforts continue.

A massive flash flood, believed triggered by a glacial collapse, swept through the Bhotekoshi-Trishuli river basin last Wednesday, destroying villages across a Himalayan valley. Nearly 12,000 people have been rescued, Nepal's disaster management agency said. Thousands more remain missing, including hundreds of foreign nationals from India, Britain, Australia, the United States and Malaysia.

The UN secretary-general's spokesman said the immediate priorities are delivering aid, recovering bodies, tracing missing relatives and reunifying separated children. Rescue teams continue efforts to reach potentially hundreds of workers believed trapped in Nepalese hydropower tunnels; recent reports indicated survivors were found in one tunnel.

Infrastructure damage is hampering relief efforts. The UN's Office for the Coordination of Humanitarian Affairs said more than 40 bridges were destroyed, cutting access to affected areas. Remote communities rely on army helicopter flights for supplies. Villages face shortages of fuel and electricity.

In Nepal, nearly 3,500 people are homeless across 27 temporary shelters—many schools, disrupting education. These sites are in Nuwakot and Rasuwa districts. The OCHA warned that overcrowded shelters, contaminated water and damaged health facilities are raising disease risk during the monsoon season. UNICEF said at least 22,000 children urgently need safe drinking water, sanitation and hygiene support.

On the Tibetan side, Chinese rescue teams are searching for over 500 missing individuals. They have not yet found survivors at Gyirong Port, the main Nepal-Tibet crossing. Chinese state media said rescuers using heavy machinery have reopened the route to the border crossing and cleared debris, expected to accelerate the search.

Beijing, which maintains tight control over Tibet, has released information through state media showing devastation but few details about victims or impact on local residents. Foreign journalists cannot travel to Tibet without official permission.

International assistance is mobilizing. Experts from China and India are building temporary bridges to remote areas, while drones scan hard-to-reach zones for survivors. Yahia said delivering aid is "very, very difficult" and the UN may use "very simple means" like porters to transport supplies as quickly as possible.

The Nepalese government and UN agreed to launch a four-month humanitarian flash appeal for health and shelter needs. Prime Minister Balendra Shah said the government is focused on protecting survivors. Nepal, a largely rural nation of 30 million with limited resources, faces significant challenges in managing the aftermath.