More than 150 dead in Nepal floods, Australian among hundreds missing

At least one Australian is missing after a deadly flash flood hit the Tibet-Nepal border, according to local authorities.

The torrent of water swept through the Himalayan border region on Wednesday morning, local time, killing at least nine people in Nepal so far.

Nepal's tourism board said at least 384 travellers, including 291 foreign nationals, had been reported missing.

The list of foreigners unaccounted for, which has been seen by the ABC, includes one Australian.

The Department of Foreign Affairs and Trade has yet to respond to the ABC's questions.

Nepal's foreign minister said an earthquake caused an avalanche that triggered the flood along the Bhote Koshi river in Rasuwa, according to local media reports.

Broadcast images showed crumbled homes, floating cars and a metal bridge being washed away in the Nepal flood waters.

"There could be heavy casualties or loss of property," said district administrator Narendra Pariyar, who urged dwellers on the banks of the Bhote Koshi river to move to higher ground, after reports of villages and project sites being swept up.

Nepal's rescue helicopters would be unable to land in the affected areas until the waters recede, army spokesperson Raja Ram Basnet said.

On the Tibetan side of the disaster, Chinese officials said they feared "major casualties" in the the county of Gyirong after a mudslide hit a land crossing.

President Xi Jinping urged "all-out" search efforts for the missing as well as stronger monitoring and early warning systems to prevent secondary disasters.

Chinese state media said access to the the area was cut off and communication channels were down, but it was expected dozens of people could be killed.