In an interview with the Spanish climbing publication Desnivel, he said that up to 90 per cent of those passing through Everest base camp could be using chemical assistance to climb the world's highest peak. [ Read the story here - Spanish only]

Mr Messner, 68, one of the world's greatest mountaineers, was the first to conquer Mount Everest without using supplementary oxygen. He was also the first to reach the summit solo, a feat he achieved from the Tibetan side in 1980, also without the use of oxygen canisters.

He said he did not include bottled oxygen as a drug, describing its use as "medical treatment."

"For the moment, nobody has studied doping on Everest,” he said, during the recent International Mountain Summit in south Tyrol.

“If a doctor were at base camp, and took samples, he would find that 90 per cent of mountaineers are doped."

Nick Colton of the British Mountaineering Council said he was “not aware” of mountaineers being doped while on Everest.

However, ExplorersWeb, a website dedicated to exploration, described medical drug use as an “open secret” on some peaks.

It cites the use of drugs such as Diamox, which is used to speed up altitude acclimatisation, and Decadron, a steroid that relieves acute mountain sickness.

In the same interview, Mr Messner lamented the coverage of mountaineering in the mainstream media, saying that they concentrated on negative incidents.

“It makes me very sad that the media only talk about mountaineering if there is a big tragedy, like the one on Everest in 1996… that’s not a good thing.”

As well as his conquest of Everest, Mr Messner was also the first climber to reach the summit of all 14 peaks more than 8,000 metres high.

He first climbed Mount Everest in 1978, almost 25 years after the mountain was initially conquered by Edmund Hilary and Tenzing Norgay.

On May 29 this year, it will be 60 years since their historic ascent. More than 3,000 climbers have since reached the summit.

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South Tyrol with Reinhold Messner

Having scaled most of the world’s greatest peaks, Reinhold Messner is building a unique range of museum experiences in his Dolomite homeland. Adrian Bridge heads to South Tyrol to meet him ... and his yaks.