The floods left thick mud and debris across parts of a river valley in Rasuwa District, affecting farmland and settlements across the surrounding hillsides.

The Nepal Tourism Board said 384 tourists and travellers were out of contact in Rasuwa, including 291 foreign nationals and 93 Nepali citizens.

The preliminary list includes travellers from India, Britain, the United States , Malaysia and several other countries.

The floodwaters swept through the Bhote Koshi River corridor on Wednesday morning, hitting Timure and Syafrubesi and damaging roads and bridges leading to the Rasuwagadhi border crossing.

The disaster also affected the border area around Gyirong. Chinese authorities said a mudslide caused major casualties and left people unaccounted for at Gyirong Port at around 10:30.

China's Ministry of Emergency Management deployed hundreds of firefighters and engineering rescue personnel to the affected area, along with emergency equipment and relief supplies.

Nepalese authorities warned residents to stay away from riverbanks along the Bhote Koshi, Trishuli and Narayani rivers as rescue teams worked to reach affected communities.

An earthquake was also reported in the Himalayan region on Wednesday. Early reports suggested it may have triggered an ice-and-rock avalanche that blocked a river before a large surge of water broke through and rushed downstream.

Authorities were still working to determine the precise chain of events behind the disaster.

Officials also stressed that the missing-person figures remain preliminary and are being checked with travel agencies, guides, local authorities and security agencies.

They urged people not to assume that those listed as missing were dead until their whereabouts had been confirmed.