An avalanche near the Mount Everest base camp has killed at least 12 people in one of the deadliest incidents on the world's highest peak.

The avalanche, the deadliest in eight years, hit the most popular route to the mountain's peak about 6:45am local time on Friday, killing the Nepali guides and injuring three more.

Four people are still missing and presumed buried under snow, the country's tourism ministry said.

Earlier, Lakpa Sherpa, from the non-profit Himalayan Rescue Association, told AFP by telephone from Everest base camp that he saw at least 11 bodies brought to the camp and was told to expect three more.

Scottish filmmaker Ed Wardle put the death toll at 16 - including five from his own party - with more badly injured.

"One of the most horrific sites I ever saw on Everest was seeing the bodies being airlifted on long lines below the helicopters," he told Britain's Channel 4 News.

The president of the Nepal Mountaineering Association, Ang Tshering Sherpa, said the avalanche struck at an altitude of about 5,800 metres.

Tourism ministry spokesman Mohan Krishna Sapkota said all the climbers were of Nepali origin.

He said they were preparing the route to the summit ahead of the summer climbing season, which kicks off later this month.

"The sherpa guides were carrying up equipment and other necessities for climbers when the disaster happened," Mr Sapkota said.

Himalayan Climbing Guides Nepal, a Kathmandu-based firm, said two of their guides were among the dead.

Guide tells of 'block of ice that fell from above'

A young Nepali guide has recalled being "trapped" after the avalanche came crashing down the icy slopes.

The force of the avalanche fractured 22-year-old Dawa Tashi Sherpa's ribs and broke his shoulder blades, leaving him buried in neck-deep snow.

"I don't know how I survived," Dawa Tashi Sherpa said.

The summit of Mount Everest is 8,848 metres high. ( Reuters: David Gray )

Despite being hit by the full force of the avalanche, he says he managed to breathe and was conscious, though suffering from hypothermia.

"It came out of nowhere, this huge block of ice that fell from above, flying right at us," he said.

"I wanted to run but there was no time, we were just trapped."

He was eventually found by rescuers and airlifted to Kathmandu's Grande International Hospital after being rescued.

"I am the luckiest man alive," he said from his hospital bed.

His doctor, orthopaedic surgeon Chakra Raj Pandey, says he expects his patient to make a full recovery.

"He has suffered multiple wounds, but he is stable," Dr Pandey said, expressing optimism that his fractures would heal in about six weeks.

Dawa Tashi Sherpa was among a large party of sherpas carrying tents, food and ropes to head out for the early morning expedition.

Sherpas had no chance to hide: Australian mountaineer

Perth-based mountaineer Margaret Watroba witnessed the avalanche as she was setting out for an exercise climb.

"We were at the base of the ice fall. We saw the avalanche. It was huge from left to right and we knew the sherpas were there. It was total disaster," she told ABC News 24.

"If we left camp say an hour, two hours earlier we wouldn't be at the launch site - we'd be at the bottom of the avalanche.

"The avalanche happened at the top of the ice. The rock collapsed."

A tourism official said three rescue helicopters were deployed to search the area and carried the injured to safety.

Ms Watroba, the only Australian woman to have conquered the world's highest mountain from both sides, said the sherpas involved in the avalanche were on a ladder and "had no chance to hide anywhere".

"The feeling at the moment is dreadful, absolutely dreadful because this is in the history of Mount Everest the biggest one-day disaster," she said.

"The helicopter will go through with a long swing and they wrap the bodies. It's a very difficult situation.

"The bodies are wrapped and flown to the base camp where we've got a medical doctor and the helipad."

Every summer hundreds of climbers from around the world take advantage of optimal conditions to scale peaks in the Himalayas, including Mount Everest.

Last year eight people were killed during the climbing season.

More than 4,000 climbers have scaled Everest's summit since it was first conquered by Sir Edmund Hillary and Tenzing Norgay Sherpa in 1953.

Almost 250 people have died on the mountain since then.

ABC/Wires