The chief of Nepal's mountaineering association says human waste left by climbers on Mount Everest has become a problem that is causing pollution and threatening to spread disease on the world's highest peak.

Ang Tshering told reporters Tuesday that the more than 700 climbers and guides who spend nearly two months on Everest's slopes each climbing season leave large amounts of feces and urine, and the issue has not been addressed. He said Nepal's government needs to get the climbers to dispose of the waste properly so the mountain remains pristine.

Hundreds of foreign climbers attempt to scale Everest during Nepal's mountaineering season, which began this week and runs through May. Last year's season was canceled after 16 local guides were killed in an avalanche in April.