Five U.S. mountaineers climbed the 8,850 metre (29,035 feet) Everest, the world's highest peak, in May 1963. Two went along the untested West Ridge route and three along the traditional South East Ridge route, also known as the South Col route.

This year, two climbers in a nine-member team led by Corry Richards will climb the difficult West Ridge route, while the others will go along the Southeast Ridge route, pioneered by New Zealander Sir Edmund Hillary and Tenzing Norgay in 1953.

Conrad Anker, 49, a member of the team and a two-time Everest climber, said that if weather and physical abilities allowed, both groups would try and meet at the summit.

"That will be the plan," Anker told Reuters before leaving for the mountain in March.

Another American team consisting of four climbers led by James Ryrie Norton will also be on the West Ridge route, Nepal's Tourism Ministry said.

"These two expeditions are trying to replicate what the U.S. team in 1963 did on Everest," said Elizabeth Hawley, Kathmandu-based historian and an unofficial authority on Everest.

Hawley, 88, unofficial arbiter of climbing related disputes and chronicler of Everest climbs, considers the 1963 American ascent to be the biggest Everest milestone after the pioneering feat of Hillary and Norgay because the route is long and so difficult it is rarely used today.

"They will make a film ready for next year's 50th anniversary," the bespectacled Hawley said of the U.S. climbers.

AIMING FOR RECORDS

Other U.S. climbers are aiming for records.

Dave Hahn, 50, from Taos Ski Valley, New Mexico, will try to make his 16th ascent along the normal route, Hawley said. The record is 21 climbs by Apa Sherpa, a Nepali mountaineer.

During the current March-May climbing season, 40-year-old Chad Kellogg, from Seattle, Washington, is trying to become the fastest climber on Everest.

The record is now held by Nepali Pemba Dorje Sherpa, who climbed the mountain in 8 hours 10 minutes from its base camp which is located about 5,300 metres (17,390 feet).

For an average climber it takes several days to cover the distance after weeks of acclimatisation in altitude.

Mount Everest has been climbed more than 5,600 times by nearly 3,700 people since it was first scaled by Hillary and Norgay. The climbers include 321`women, a 13-year-old American boy, a 76-year-old man, a blind person and a man with artificial limb.

At least 231 people have died on its slopes.

(Reporting by Gopal Sharma; editing by Elaine Lies and Sanjeev Miglani)

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