Everest climbers

Everest climbers worried about oxygen bottle theft

They say it could threaten the lives of mountaineers because they each have a set supply for weather and traffic-related delays, as well as for the descent.

The concerns have been raised as the last groups of mountaineers wait for the weather to clear for their final push to the summit.

Experts say crowds of mountaineers, with many inexperienced climbers and unqualified guides, have also contributed to the situation.

"It is becoming a serious issue up there," Nima Tenji Sherpa, a mountain guide just back from Everest, told the BBC.