What led 35 Australians to the remote Nepal valley hit by deadly floods?

At least 34 Australians are missing after a flood and landslide disaster on the Nepal-Tibet border, with many caught up in one of Nepal's most popular trekking regions, the remote Langtang Valley.

The disaster has killed at least 160 people with hundreds more missing.

Some 403 tourists — 341 of them foreigners — were unaccounted for several hours after the disaster struck on Wednesday , according to Nepal's tourism ministry. Chinese rescuers are searching for hundreds more in Tibet.

It's feared many more are missing or dead, as rescuers battle a lack of infrastructure and remote, mountainous terrain to search through mud and debris.

Foreign Minister Penny Wong spoke about why so many foreign nationals were in the area in a press conference on Thursday afternoon.

Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.

"It is well–known that this area, people are not only going there for trekking but also for spiritual reasons, so you would anticipate that the foreign nationals who were in the region would have been there for a variety of reasons," Wong said.

She said it may take time for the Australian government and Nepalese authorities to understand how many people are missing or dead.

"I can only outline the numbers we are aware of today," Wong said. "The numbers of foreign nationals are higher and as yet we do not have any further information about if there are any more of those who are Australian.

"We will continue to try to ascertain if there are any Australians who are not accounted for over and above the 34 that we are aware of."

United States-based tourist company Himalayan Glacier confirmed 15 Australians who were on one of its tours are missing and unaccounted for in the Langtang Valley.

The company's chief executive said he had not been able to contact the group of 47 people — which includes 15 Australians, nine Nepalese, two from the United Kingdom, two from Singapore and others from the US and Russia, the ABC has reported.

Among the Australians missing are nine men and six women. The youngest are boys aged 14 and 11, and the oldest is a woman aged 64.

The flood hit Syabrubesi, is the starting point for the popular Langtang trek, as well as other areas used by travellers for Hindu pilgrimage to Kailash Mansarovar.