A flash flood on the Nepal‑Tibet border on Wednesday left more than 400 travelers, including 33 British citizens and a 13‑year‑old girl, missing, according to Nepal’s tourism board.

The flood occurred at about 8:30 am local time on the Tibetan side of the Bhote Koshi River after a mudslide collapsed into the river, causing severe flooding on the Nepali side.

At least 341 foreign nationals were unaccounted for, and the British missing included three men aged 65, 64 and 52 and seven women aged 44, 47, 51, 60, 63, 63 and 65, travel logs showed. The tour operator Alpine Eco Trek said a 13‑year‑old girl was among the missing British nationals and also listed two Irish citizens. Four Nepali guides aged 38, 35, 45 and 29 were also reported missing.

Kumar Adhikari, manager of Alpine Eco Trek, said the group had been crossing into Tibet from Nepal when they became trapped at the border, and that the tour guides’ phones went offline at 8:40 am. He added that the group had hoped to find safety inside the border immigration office. Chinese government video later showed flooding on the Tibetan side.

Police in Nepal reported 157 bodies recovered and more than 40 people injured in hospitals. The tourism board said more than 100 of the missing had not yet had their nationality confirmed. Officials in Tibet expressed concern about possible major casualties, and the Rasuwa district authority urged tourists to exercise caution, remain in safe areas and move to higher ground if necessary, while advising travelers to keep in contact with hotels and travel agencies and to postpone journeys.

The UK foreign secretary, Ed Miliband, said he was deeply concerned and that his thoughts were with those affected and with British nationals and their families. The British embassy in Kathmandu urged people in the affected areas to follow local advice, and a joint statement from the embassies of Australia, the European Union, Finland, France, Norway and Switzerland expressed solidarity and called for people to follow local guidance.

Authorities continued to monitor the situation, and travelers were advised to await further updates before planning trips to the region.