Seven Britons were among 19 people killed when a plane heading for the Everest region crashed in Nepal's capital, the Foreign Office has said.
The Sita Air plane came down minutes after taking-off from Kathmandu for Lukla. The Britons' next of kin have been contacted, the FO says.
Officials said the aircraft crashed into a river bank and caught fire.
The start of autumn marks the beginning of the Himalayan trekking season, which is popular with Western climbers.
Aviation officials said five Chinese nationals and seven Nepalis, of whom three were crew members, were on board.
The Britons - who arrived in Nepal on Wednesday - have been identified by local travel company Sherpa Adventures as;
- Stephen Holding, 60, from Barlaston in Staffordshire;
- Raymond Eagle, 58, from Macclesfield in Cheshire;
- Timothy Oakes, 57, from Winwick, Cheshire;
- Christopher Davey, 51;
- Vincent Kelly, 50, and his brother Darren, 45, who were originally from Lostock, Bolton;
- Benjamin Ogden, 27, who lived in London.
Darren and Vincent Kelly are reported to have been fundraisers for the Bolton Lads & Girls Club.
Darren is thought to have been a semi-retired property developer and businessman who recently moved to Isle of Whithorn in Dumfries and Galloway.
Family members gathered at the Lostock home of Vincent Kelly told reporters they did not wish to comment, saying "It's too early to talk right now".
Angie Gaunt, the wife of victim Timothy Oakes, told the Press Association he was "on a trip of a lifetime with an old school friend".
Ms Gaunt said her husband worked in education and "died doing something he always wanted to do".
"He was a mountaineer and he always wanted to go to Everest base camp, not climb it, to go to the base camp, and that's what he was doing," she added.
Another of the passengers, Raymond Eagle, was 58 and had worked as a support worker at Cheshire East Council.
A council spokesman said he "enabled people with disabilities to live independently in their own homes".
One of his neighbours, Christopher West, told reporters Mr Eagle was a keen runner who "liked his sport, his running, and holidays. He's there one minute and the next minute he's off. He was a nice guy."
The youngest victim, 27-year old Ben Ogden, was a graduate of Oxford University and had recently qualified as an associate for London-based international law firm Allen & Overy.
A spokesman for the company said: "As well as being an excellent lawyer, Ben was a very popular member of the firm.
"It was clear to everyone that he had an incredibly promising career ahead of him. Ben will be deeply missed by all who knew him."
The group were due to complete their expedition in mid-October.
The cause of the crash has not yet been officially confirmed.
The general manager of Tribhuvan International Airport, Ratish Chandra Lal Suman, said in a statement that the plane, a twin-propeller Dornier, had struck a vulture soon after take-off.
Prime Minister David Cameron, who is on a trade trip to Brazil, described the accident as "absolutely horrific".
"I know our Ambassador in Nepal is on the case and increasingly on the spot dealing with it.
"Obviously we'll have to find out exactly what happened. But a deeply, deeply tragic case," he added.
The British ambassador to Nepal, John Tucknott, told the BBC: "Our priority now is with the families and the relatives of the victims and our thoughts and prayers are with them.
"The authorities in the UK are in touch with the families. If family members wish to come to Nepal, we stand by to offer them every assistance we possibly can at this very difficult time."
Explore Worldwide, the Farnborough-based adventure travel company, confirmed that the Britons were its clients.
Ashley Toft, the company's managing director, said: "We are devastated by this news. Our thoughts are very much with the families of those affected, both in the UK and in Nepal.
"The basic facts are that Sita Air operates scheduled flights and is approved by airline authorities. The weather was good. The plane was departing for Lukla and our passengers were heading for Everest Base Camp at the start of their trek."
He said the company was sending a senior manager to Nepal to help to support their team in Kathmandu and assist the family of the Nepalese guide, whom they "knew very well".
British mountaineer Alan Hinkes told the BBC he had taken the flight from Kathmandu to Lukla many times: "The landing strip in Lukla is a bit like an aircraft carrier with a mountain at the end of it, with a 1,000ft drop at the end of the runway. Normally crashes happen at that end." .
He added: "It is not the safest place to fly, I must admit, but it is what you have to do to get into the mountains."