Helicopter firms are carrying out unauthorised sightseeing flights over the upper reaches of Mount Everest, Nepalese media say.
Sherpas have expressed concerns that vibrations caused by the helicopters could trigger avalanches.
Tourist flights are not allowed to places above Base Camp which is at an altitude of 5,364 metres (17,600ft).
But helicopter companies say they only overfly sights like the Khumbu Icefall and their flights are allowed.
There had been no expedition on Everest for the past two years because of a series of disasters.
Sixteen Sherpas died on their way to Camp One in an icefall in 2014. At least 18 climbers died at Base Camp after a major earthquake triggered a huge avalanche last year.
After the 2014 disaster, authorities moved the climbing route to the middle of the Khumbu Icefall.
It is a treacherous section that mountaineers must cross on their way up to the summit of Everest.