Nepal is so short of oxygen canisters that it has asked climbers on Mount Everest to bring back their empties instead of abandoning them on mountain slopes, said an official, as it struggles with a second wave of the coronavirus.

The Nepal Mountaineering Association (NMA) has asked the climbers to help Nepal deal with a surge in Covid-19 cases that has brought the country's fragile healthcare system to a breaking point, as it has in neighbouring India where deaths held close to record highs.

Kul Bahadur Gurung, a senior official with the NMA, said climbers and their Sherpa guides were estimated to have carried at least 3,500 oxygen bottles this season.

"We appeal to climbers and sherpas to bring back their empty bottles wherever possible as they can be refilled and used for the treatment of the coronavirus patients who are in dire needs," Gurung told Reuters.