KATHMANDU -- Everest is overcrowded and has lost its challenge for true Alpinists, says Austrian Peter Habeler, who along with Italian reinhold messner became the first to ascend the summit without bottled oxygen 25 years ago.

In an interview with AFP in Kathmandu, Habeler was dismissive of the 25 teams currently tackling Everest as part of the celebrations marking the conquest of the mountain by Tenzing Norgay and Edmund Hillary on May 29, 1953.

"Alpinists don't think very highly of them: I'm sorry to say that, but it's true," said Habeler, now 60.

He also believed the Nepalese government should resist placing so much emphasis on Everest and instead start promoting other, more challenging Himalayan peaks, AFP reported.

"Of course this year they hope to make money out of Everest, but it is a little sour spot what is happening on Everest now. There are too many people there. It is nothing to do with real adventure anymore," he said. "It is peanuts, climbing surrounded by Sherpas and using oxygen. You cheat the mountain. People are now racing to be the fattest, the thinnest, the youngest, the oldest up Everest ... This has nothing to do with alpinism anymore."

For him, to use supplementary oxygen is to take the easy way out.

"Oxygen makes the mountain 2,000 meters lower -- it is like climbing to 6,000 meters rather than 8,000 meters," he said.

"It has nothing to do with real adventure," added Habeler, who had just arrived in Katmandu to lead a German trekking group to Everest base camp as part of the Everest golden jubilee celebrations.

What he and Messner had done, he added, was "real adventure".

"There were more people telling us that it couldn't be done than there were people believing it could," said Habeler.

But because some sherpas had climbed above 8,500 meters (27,880 feet) unaided by oxygen bottles, they believed they, too, could get away with it. "The idea was to sneak into the death zone (above 8,000 meters) and out again as quickly as possible. This we could do because we weren't weighed down by oxygen tanks and heavy equipment. We had just our packs, which meant we could move quickly."

The main pressure, he added, was psychological. "We had no idea of the effect on the body of an altitude of 8,840 meters (29,002 feet -- the height of Everest)," he said. "So we just took it 40 meters at a time. We climbed 40 meters (yards), then allowed the body to adjust, then climbed another 40 meters, until we got to the top."

Once they had achieved the feat, on May 8, 1978, the trend was set and around 100 people have since summited without supplementary oxygen.

But Habeler will not take anything away from Hillary and Tenzing.

"What they did was also real adventure," he said, acknowledging that he and his Italian climbing partner had benefited from knowledge gained during the first summit and the hundreds that followed before they had set out on their own Everest quest. "Hillary and Tenzing did a really fantastic job," he said. "What they did was also real adventure." So who are the real kings of Everest?

"There are so many kings and queens ... in fact every person has their own Everest," Habeler said.

Other climbers voiced similar views.

"There are so many different challenges on Everest," said Ang Phurba Sherpa, vice president of the Nepal Mountaineering Association, who has himself stood atop the world's highest peak. "The struggle is always against yourself and whatever challenge you have set for yourself."

For Wongchu Sherpa, president of the Everest Summiters Association, the answer to the question is straightforward -- Tenzing and Hillary are the true kings of Everest. "To be the first one to do something is to be the first, to be second is second. That's all there is to it."

That view, however, hasn't stopped him devoting the past year to ensuring a memorial is erected on the outskirts of Kathmandu to the Sherpa many Nepalese would argue is the greatest Everest mountaineer of them all -- Babu Chhiri.

The "snow emperor" as he was known, climbed 10 times without oxygen, holds the record for the fastest climb from base camp to the summit -- 16 hours 56 minutes -- and is the only one known to have slept on top of the world during a 21-hour 30-minute Sojourn at the summit.

He died tragically in 2001 after falling into a crevasse on Everest. "He was very special," said Wongchu, who has also commissioned a statue of Chhiri to be placed atop the memorial. "Very, very special."