The number of Australians missing since the catastrophic Nepal-Tibet flood has dropped from 43 to 38, the Department of Foreign Affairs and Trade confirmed on Wednesday.
Labor minister Anne Aly said the government was "very concerned" for those who were yet to be located.
"We hold grave concerns for those 38 Australians still missing," she told ABC TV.
"There are real logistic issues, including communications, to find out where people are.
"For those families that are still waiting ... we'll continue to do what we can to try and locate those people."
Five Australians were confirmed safe by officials in Nepal and Tibet, while three others were located outside the crisis zone, the government said.
The citizens hadn't been in contact with their families or next of kin since the disaster and their welfare could not initially be confirmed.
One Australian in Tibet made contact with authorities on Tuesday and was receiving support from consular officers.
The department has fielded nearly 800 calls in relation to the disaster.
Foreign Minister Penny Wong previously said nine Australians were missing on the Chinese side of the Nepal-Tibet border.
The family of one missing Australian, Luke Costanzo, released a statement on Tuesday night about the "unimaginably difficult situation" that had confronted them.
The 30-year-old had been visiting Tibet's Mount Kailash on a pilgrimage trek with the non-profit Isha Foundation.
He was making his way back to Kathmandu on the final day of his journey when the floods hit.
"We can do nothing but continue hoping for a miracle that Luke, and the others who remain missing, are found alive and well," Mr Costanzo's family said.
The bodies of the flood victims have begun to be buried in mass graves in Kathmandu after DNA samples were taken.
Heavy rain can be seen creating muddy conditions for army personnel and rescue workers as they bury the unidentified victims.
At hospitals and relief centres in Kathmandu, families and loved ones gather to search for missing relatives and assist with efforts to identify the dead.
More than 1000 people have been confirmed killed after a glacier collapse sparked a huge mudslide and flash flooding near the Gyirong border crossing in the Himalayas on August 26.
Victorian Tibetan community member Tenzin Norzin told AAP he feared the number could be far higher, adding the global community was hearing "less and less" of the impact of the floods across the border in Tibet.
Experts say satellite imagery showed warning signs of a potential ice avalanche were evident days before a glacial collapse and landslide triggered the catastrophic events in the Lhende Khola River.
A report published by international scientific consortium HiRISK on August 28 analysed a series of "pre-event indications", concluding the ice surface "sped up" prior to the avalanche and melted water had turned "visibly brown" by August 24.
"There is also some indication of a crack propagating into the surrounding bedrock slope in the days before the event," the paper read.
Even if warning systems were in place, the speed of the avalanche meant communities at the border checkpoint would not have been able to be evacuated in time, the report said.
However, a "significant number of lives" could have been saved if warning systems had been implemented further downstream, where more than 10 minutes warning could have been given, the authors said.
The floods impacted almost 13,000 buildings and washed away 40km of highway and at least 68 bridges, satellite data accessed by HiRISK shows.
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