The number of people missing in Nepal after a massive flash flood in the Himalayan region has risen to 826, according to authorities, bringing the total number missing in Nepal and China to more than 1,300.

Nepalese police put the death toll at 162, with more than 40 injured people being treated in hospitals. China has reported three deaths and 558 people missing.

The flooding on Wednesday sent huge amounts of mud and rock through the mountainous border region along the Bhotekoshi river, sweeping away bridges, damaging dams and burying homes.

Rescue teams in Nepal and China continued searching for missing people, but thick mud was hampering operations.

The cause of the flood wave remained under investigation.