Story highlights Veteran climber says the Hillary Step, a key feature near the summit of Everest, has collapsed

But authorities in Nepal insist the famous rock face is still intact

Three climbers died while attempting to reach the summit of the mountain this weekend, another is missing

(CNN) Authorities in Nepal have denied reports that the famed "Hillary Step" on Mount Everest has collapsed, despite a veteran climber saying he saw it first hand during an ascent last week.

Mountaineer Tim Mosedale, from Everest Expedition , said he passed the sheer rock face near the summit on May 16 and all that remains of it are some blocks, "probably a few tonnes each," that pose a potential danger to climbers.

Named after Edmund Hillary, the first climber to conquer the mountain with Tenzing Norgay Sherpa, the "Hillary Step" is considered the final test of endurance for Everest climbers.

The large rocks were "on quite an incline," Mosedale said. "My suspicion is that if anyone was to try and clamber over that remaining rubble and debris that it would cause it to move."

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"It would probably be quite unstable, and would cause significant hazard to anyone who was below the climber. So really I think it's an area to be avoided now," he said.

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