Families of missing UK nationals have flown out to Nepal to search for their relatives.
The death toll from the floods in Nepal and Tibet has risen to at least 475, with several hundred people missing, including 537 tourists.
Among the British nationals reported missing are a 13-year-old girl and 14-year-old boy. On Friday, Nepalese authorities released a list of the names of all known missing tourists, 33 of which are British nationals.
The rush to find survivors comes amid warnings of further flooding across the region.
Prime Minister Andy Burnham said the UK has offered £5m to help the Nepalese government following the floods, saying it was a “very distressing and devastating situation”.
He had previously urged Britons in the region “to follow guidance from the local authorities and follow our travel advice”.
Speaking on Thursday, King Charles said he and the Queen were “heartbroken” and sent their “most profound sympathy” to those affected.
As rescue efforts continue, details of the missing are slowly emerging.
Fishtail Tours and Travels confirmed Leena Bector, from Slough, was among 27 travellers linked to the tour company who remain unaccounted for.
Her husband, Bhupesh Bector, told The Times: “I know that she’s in Nepal for sure, so even if they find her today or tomorrow, I need to be there.”
Essex nurse Rajendra Pudasaini said his relatives were “swept away” by the floods.
“My wife’s auntie and uncle, and their granddaughter and her husband are missing, and my godson as well,” he told PA Media.
“They’re gone. The speed the water came, they couldn’t be saved, they were just swept away.”
Sarada Simkhada, a senior nurse at Darent Valley Hospital in Kent, is also among the missing, according to a local councillor.
The Times said Simkhada was “following in the footsteps of thousands of Hindus this month in making the spiritual journey to Mount Kailash”.
Tatajana Phillips, from Folkestone in Kent, told the BBC she has not been able to contact her sister who was near the Nepal-Tibet border when devastating flash flooding hit.
She said the last known location of her sister Julija Jakovicka was in the border area an hour before the flash floods struck.
“Then there is no more news,” she told the BBC.
Phillips said her sister, a mother-of-two living in Germany, was in the country for a yoga and meditation retreat.
“We are terribly worried,” added Phillips’ husband Ben. “We just know where they were and that’s really tough.”
Pramod Poudel, who lives in Uckfield in East Sussex, told the BBC he has not heard from his family since the flood hit on Wednesday.
“It’s a very, very difficult time for me and for my family and my country at this moment, but obviously I have to go and see what’s happening there,” he said.
Poudel, who goes by the name Pedro, said he is travelling home to Nepal because “my family needs me”.
University of Kent graduate Nabhi Das from Streatham in South London has also been widely reported as missing Nepal.
Several of those missing had been making a pilgrimage to the sacred Hindu site of Mount Kailash, Nepalese tour operator The Trekkers’ Society said.
The operator said nine British nationals on one of its tours to the site were among those unaccounted for, including four males, aged 14, 50, 50 and 54, and five females, aged 40, 46, 50, 50 and 53.
Tour companies including Alpine Eco Trek, The Trekkers’ Society, Himalayan Glacier US, Kailash Journeys and Fishtail Tours have reported missing British nationals while on trips with the companies.
Alpine Eco Trek said it has not been able to establish contact with 12 Britons who were booked on a tour to Mount Kailash and were in the region when the flash floods struck.
The company’s travel logs which were shared with the Press Association, with a 13-year-old girl the youngest person missing.
Four of the firm’s Nepali tour guides are also missing.
The flood hit early on Wednesday in Rasuwa, just north of Nepal’s capital Kathmandu.
Preliminary information suggested it was caused by an earthquake, but the US Geological Survey said additional analysis indicated “the seismic energy was instead generated by a landslide.”
It said a magnitude 5.2 seismic event caused by a “glacial collapse and debris flow” occurred near the border at 08:37 local time (03:52GMT) on Wednesday.
Watch: What caused the Nepal-Tibet flash floods?
What we know about deadly Nepal-Tibet floods