KATHMANDU: A decades-old mystery over whether Britain's George Mallory scaled Mount Everest three decades before Sir Edmund Hillary may remain unsolved, an American climber investigating it said on Wednesday.

Conrad Anker, who discovered the frozen body of Mallory eight years ago, and his British mate Leo Houlding scaled the 8,850 metre summit last week to recreate the pioneering attempt by Mallory in 1924.

Although they wanted to use only 1920s gear as part of their probe, they ended up wearing modern clothes due to the cold. But they succeeded climbing the Second Step, or the most difficult stretch to the top, without a ladder.

Mallory and his colleague Andrew Irvine, who also disappeared in the mountains, did not have access to the kind of special ladder required to overcome the 100-foot (30-metre) vertical rock formation.

On Wednesday, Anker and Houlding said their ascent showed it was “technically possible” for Mallory and Irvine to climb the mountain without the fixed ladder.

But they could not establish it conclusively, they added.

“It is still a mystery. It is good to have mysteries,”

Anker, 44, said after returning to the Nepali capital.

If Mallory and Irvine did make it they would be the first humans to stand atop Mount Everest, 29 years before New Zealander Sir Edmund Hillary and Tenzing Norgay Sherpa who climbed from a different route in Nepal in 1953.

But even if they did, Hillary and Tenzing were the first to climb it and return safely, Anker said.

“You have to get to the top and then return safe and sound,” he said. “It is a very simple rule of climbing.”

“We need mysteries in life,” said Houlding, 27, speaking from outside their hotel in Kathmandu. “If we knew the answer or if they had made it in 1924 and we knew that then it would not be the story that it is.”

“The reason that it is such a huge international story is because it is a perfect mystery,” he said.

More than 2,000 climbers have reached the Everest summit since 1953 and at least 207 are known to have died on its slopes. About 520 people climbed the mountain this year, the highest in the most popular mountaineering season.

—Reuters