Air accident investigators from the UK are heading to Nepal to investigate the plane crash which killed seven Britons.
A group of British tourists are among 19 people who died today in a plane crash in Nepal.
The Walking with the Wounded charity expedition to Mount Everest began with a six-mile trek in the Himalayas.
After an avalanche swept down a slope of Mount Everest killing at least nine mountaineers, helicopters and food have been sent to base camp to take away the dead and help with rescue efforts.
Some mountaineers remain missing on the mountain.
Footage from NBC News at Mount Everest:
An avalanche that swept down a slope of Mount Everest at the beginning of the main climbing season, has killed nine Nepali mountaineering guides, a Tourism Ministry official said.
The avalanche hit the most popular route to the mountain's peak and three Nepali guides were injured and some people may be missing, Tilak Ram Pandey, an official at the ministry's mountaineering department said.
Madhusudan Burlakoti, a senior official at the ministry, said helicopters and rescuers on foot had been sent to the site.
Six local guides have been killed and nine more are missing after an avalanche swept a route used to scale the world's highest peak, a Nepalese tourism official said.
The avalanche hit just below Mount Everest Camp 2 around 6.30am local time, Krishna Lamsal said.
He added that four bodies have been recovered and rescuers are digging two more out of the snow. Nine other Sherpa guides are unaccounted for and believed to be buried in the snow.
All those killed and missing had gone early in the morning to the area to fix ropes for climbers along the route to the 29,000ft summit.
Hundreds of climbers and guides have gathered at the base camp, gearing up for their final attempt to scale Everest early next month when weather conditions get favourable.
Up to five climbers are feared missing after an avalanche swept the slopes of Mount Everest and hit a route used to scale the world's highest peak.
The avalanche hit the area just below Camp 2, according to Nepal Tourism Ministry official Madhu Sudan Burlakoti.
Rescuers and fellow climbers at the base camp are heading to the area to help, and a helicopter is on the way from Katmandu.
Ang Tshering of the Nepal Mountaineering Association said four or five climbers are believed to have been buried and more injured by the avalanche.
The Nepalese government plans to open an office at Mount Everest base camp in a bid to regulate attempts on the summit more closely, the BBC reports.
The move follows a series of embarrassing episodes on the world's tallest mountain, including a fight between climbers and local sherpas in April.
Officials also plan to monitor "bizarre" record attempts, believing that some feats "don't bode well for the dignity of Everest".
"These days we see people trying to make bizarre records like, for instance, standing on their head or taking off their clothes while on the summit," said Ang Tshering Sherpa, a member of the committee that recommended the new rules.
Further restrictions on littering and helicopter flights close to the mountain are also expected.
An 80-year-old Japanese mountain climber has received a hero's welcome in Kathmandu after becoming the oldest person ever to reach the summit of Mount Everest.
Yuichiro Miura, who has undergone heart surgery four times, was greeted with garlands of flowers and a press pack in the Nepalese capital after reaching the summit late on Thursday.
"This is the greatest feeling in the world," he told family members and supporters gathered in Tokyo, speaking from the summit by satellite phone.
"I never thought I'd get to the summit of Everest at the age of 80. It was the best feeling to get here, but now I'm completely exhausted."
Miura comes from a dynasty of veteran adventurers in Japan, his father having famously skied down Mont Blanc at the age of 99.
An 80-year-old Japanese mountaineer has become the oldest man to reach the top of Mount Everest.
Yuichiro Miura, who also conquered the 29,035-foot (8,850m) peak when he was 70 and 75, reached the summit at 9:05 a.m. local time Thursday, according to his support team. Miura and his son Gota called them from the summit to report the news.
"This is the world's best feeling," Miura said. "I'm also totally exhausted."
The previous oldest man to reach the summit was Nepal's Min Bahadur Sherchan, who accomplished the feat at age 76 in 2008, just a day before Miura reached the top at age 75.
Sherchan, now 81, is preparing for his own attempt on the summit next week, meaning Miura's record may not last long.
A British climber has told how he thought he was going to die when an argument broke out on the world's highest mountain.
Photographer Jonathan Griffith said he and two friends were attacked by up to 150 of the Nepalese guides as they made their way to a camp on Everest.
He told The Sun that he and experienced climbers Simone Moro, 45, from Italy, and Swiss national Ueli Steck, 36, were left bruised and cut after the gang kicked, punched and threw rocks at them.
The three were only saved when a group of Western climbers intervened, he added.
He said: "They didn't want to talk, they wanted to finish us off.
"They picked up big rocks off the glaciers and started throwing them at us."
Mr Griffith, who is from London but now lives in Chamonix, France, claimed the argument started when an angry Sherpa leader confronted the trio and accused them of injuring one of his men, who was securing ropes on the mountain for another expedition.
Nepal officials have vowed to ensure the safety of climbers seeking to scale Mount Everest after three European climbers were involved in a fight with Sherpa guides.
Tourism Ministry official Dipendra Paudel said the government would ensure the safety and security of the climbers.
"There was a slight misunderstanding and communication gap between them," Paudel said. "This has been sorted out and the climbers are at the base camp".
Three climbers claim they were punched and kicked by Sherpa guides following a disagreement as they scaled Mount Everest.
Jonathan Griffith, Ueli Steck and Simone Moro allege the high altitude guides became aggressive after they were forced to step over the guides' fixing ropes.
The Sherpas claimed the climbers had kicked ice down onto them, injuring a guide, and a tussle broke out before the group made their way back to Camp 2.
The climbers claim around 100 Sherpa guides then grouped together and became "instantly aggressive", punching, kicking and throwing stones at them before they were saved by a group of "brave and selfless" Westerners on the mountain.
They said in a statement they "don't believe that their actions were the reasons behind such a mass attack".
"They believe that the reaction was from a far more deep rooted and long-term problem, which is the way that Nepalis feel treated by Westerners on the mountain and this was a uprising against that", the statement said.
"There is no reason to instigate vigilante rule and to try and kill three visiting climbers", it added.
The climbers also said they are "completely independent" and "not part of any commercial expedition".