Huddled in their sleeping bags, the climbers first heard the avalanche roar towards them and then the sound of screaming before being swept hundreds of metres down the slopes of "Killer Mountain".

Survivors of the weekend tragedy on Nepal's Manaslu mountain, which killed at least nine people, said the scene resembled a war zone, with an entire camp destroyed by the wall of snow.

"We were sleeping in our tent after having dinner, when all of a sudden we heard the noise of other climbers screaming. Within moments, we were hit by the avalanche," said Andreas Reiter, one of the trek's survivors.

Reiter was among a group of European adventurers who were near the peak of the 8,156-metre (26,759-foot) Manaslu when the avalanche struck. They were asleep. It was 4:00 am on Sunday.

"I witnessed one of the team members die," the 26-year-old German, who has broken his back, was quoted as telling The Himalayan Times as he recovered in hospital in Kathmandu.

Rescuers scaled down the search Monday for two French climbers and a Canadian still missing on Manaslu, the world's eighth-highest peak and one of the most challenging.

Pravin Nepal, an orthopaedic surgeon at Norvic Hospital in Kathmandu, told AFP Reiter's spinal cord was broken.

"He is undergoing an MRI test. He can speak and move his hands and legs."

Another German being treated at the hospital was being treated for frostbite, the medic said.

Also among the survivors was Glen Plake, 48, a three-time freestyle skiing world champion from California. He described the site of the avalanche as "a war zone".

"It was a major, major accident... There were 25 tents at camp three and all of them were destroyed," he told the Epic TV video subscription service.

"Twelve tents at camp two were banged up and moved around."

Plake told the company's blog he was reading when he and a companion with whom he was sharing his tent heard a roar.

"Greg looked at me and said 'that was a big gust of wind', then a second later, 'No, that was an avalanche'.

"Then it hit us. I was swept 300 metres over a serac and down the mountain and came to a stop still in my sleeping bag, still inside the tent, still with my headlamp on."

Christian Trommsdorff, of France's national union of mountain guides, said the avalanche happened at about 7,400 metres and carried away part of camp number three at 6,800 metres.

Expedition leader Garrett Madison said he and his team were sleeping at camp two, further down the mountain, when they were awoken by "snow, wind and ice penetrating our tents".

"Fortunately everybody in our group was okay. However when we climbed up to camp three shortly after to investigate we discovered the debris from a massive avalanche and found many climbers in distress," Madison wrote on the Alpine Ascents blog.

"During the rescue and recovery in the following hours we were able to coordinate and assist evacuating over a dozen climbers on 10 helicopter flights from just below camp three."

Manaslu is nicknamed "Killer Mountain" by locals because a series of snowslides have claimed the lives of scores of mountaineers since it was first conquered in 1956.

The latest deaths mean at least 62 people have died, according to an AFP tally.

It saw its worst disaster when a South Korean expedition was buried by snow while attempting to climb the northeast face in 1972. The 15 dead included 10 Sherpas and the Korean expedition leader.