A team of Nepali mountaineers will leave Kathmandu tomorrow heading for Mount Everest, the world's highest peak, where they hope to climb to more than 8,000 metres (26, 246ft) to clear the mountain's "death zone" of tonnes of rubbish and remove the bodies of dead climbers.

Though many foreign and Nepali expeditions have set out to clear parts of the mountain in the past, Namgyal Sherpa, leader of the Extreme Everest Expedition 2010, said no one had tried to clear at that height. "This is the first time we are cleaning the death zone. It is very difficult and dangerous," said Namgyal, who has climbed Everest seven times.

The zone earned its name because it is almost impossible to survive the harsh temperatures and the thin air of such altitudes, where there is a third as much oxygen as at sea level for more than a couple of days. Anyone who remains within the zone for longer will almost certainly perish.

The climbers will use special bags to collect the bodies – which lie between the South Col and the 8,850m (29,035ft) summit – before lowering them down the snow and icefields of the mountain and then carrying them across the glaciers to base camp. The expedition hopes to retrieve five bodies, including that of a climber killed two years ago.

Scores of corpses preserved by the freezing temperatures remain on the mountain, some for decades. "I have seen three corpses lying there for years," Namgyal said. "We'll bring down the body of a Swiss climber who died in the mountain in 2008 and cremate it below the base camp, for which we have got the family's consent."

In 1999 a research expedition found the remains of George Mallory, a British explorer and mountaineer, who disappeared with ropemate Andrew Irvine in 1924. Experts have long debated whether it was possible that the pair had actually reached the summit before perishing. The find did not provide conclusive evidence. A service was performed for Mallory and his body left where it was.

More than 4,000 climbers have scaled Everest, which is known as Chomolungma in local Tibetan language. Climbing has become a key source of income for Nepal, a state reduced to poverty by lengthy civil strife and misgovernment. Not only do expeditions provide employment for thousands but climbers pay high fees to the Nepali authorities for permission to venture on to the mountain, providing much-needed hard currency.

Litter on the mountain was a major environmental problem until the Nepalese government imposed strict rules requiring visitors to keep the peak clean or risk losing a substantial deposit.

The South Col, from which the attempts to reach the summit are often launched, had become known as the world's highest rubbish tip, with the snow littered with empty oxygen bottles, old ropes, food and the remnants of tents.

"The garbage was buried under snow in the past. But now it has come out on the surface because of the melting of snow due to global warming," Namgyal said, adding that some of the rubbish had been on the mountain since 1953 when Edmund Hillary, who died in 2008, made the first successful ascent of the mountain with Sherpa Tenzing Norgay.

Frozen fates

One of the most notorious disasters on Everest occurred in 1996 when eight people died within 36 hours near the summit. Three of the casualties were with an Indian paramilitary police expedition on the north side of the mountain. The rest were guides and clients on commercial American expeditions climbing the traditional South Col route.

The deaths of the five westerners was the subject of a best-selling book, Into Thin Air, and a film that depicted chaotic scenes in the "death zone" as dozens of mountaineers attempted to climb or descend the narrow summit ridge with bad weather threatening. Blizzards finally turned the upper reaches of the peak into a nightmare of driven hail and snow, trapping those who had not headed down early enough.

One of the guides, New Zealander Rob Hall, was able to talk to his wife on a satellite phone from high on the mountain. Despite being frostbitten and knowing that he was probably incapable of traversing the ropes that led to safety, he said he was reasonably comfortable and told her not to "worry too much". His body was found nearly two weeks later. The tragedy sparked fierce arguments over the commercialisation of mountaineering on the world's highest peak.