Australian officials are aware of several citizens in the impacted region, near where a huge wall of mud and rock collapsed into a river on Wednesday.
Nepali police said late on Wednesday that 157 bodies had been recovered so far.
Among those missing are 34 Australians, Reuters reports.
A Department of Foreign Affairs and Trade spokesperson told AAP they were liaising with local authorities as well as tour operators and stood ready to provide consular assistance.
"We extend our deepest sympathies to those affected by the significant flooding in Nepal and Tibet, China," the spokesperson said.
"We are aware of a number of Australians in the area and Australian officials are urgently working to confirm their welfare."
The loss of life and and destruction caused by flash flooding is devastating, Foreign Minister Penny Wong said.
"Our thoughts are with the loved ones of those killed or missing and all affected by this disaster," she said in a statement on Thursday morning.
"Officials are urgently working to confirm the welfare of Australians in the area."
Australian Ambassador to Nepal Simon Ernst released a statement together with the embassies of the United Kingdom, France, Finland, Norway and Switzerland.
"Our thoughts are with all those affected by this disaster. We express our solidarity with the people of Nepal during this difficult time," they said.
"We encourage all those in affected areas to follow the guidance of local authorities and official safety advisories as the situation continues to evolve."
