Climbers descend from camp one to base camp at Mount Qomolangma, in this picture taken on May 21, 2016. [Photo/Agencies]

RETRIEVING BODIES

Expedition organisers were assembling a rescue team on Monday to retrieve the bodies of Australian university lecturer Maria Strydom and Dutch climber Eric Ary Arnold. Strydom died before reaching the summit on Saturday, one day after Arnold perished after attaining the peak.

Apart from the three deaths, two other Indian climbers have been missing on Everest since Saturday, and hiking officials said chances of finding them alive were slim.

Another Indian woman who fell sick was being escorted to lower camps and will be evacuated by a helicopter, an agency official said.

While fatalities are not unusual, there are fears the latest casualties could again hit mountaineering in Nepal.

At least 18 people died a year ago when an earthquake sent a massive snow slide careening into Base Camp, while an avalanche in the treacherous Khumbu Icefall killed 16 guides in 2014. The back-to-back tragedies had halted climbing on Everest.

"It is a difficult and challenging climb and many people have died," Australian Foreign Minister Julie Bishop told reporters in Brisbane, adding that the government was assisting with the repatriation of Strydom's body.

Arnold Coster, the owner of Arnold Coster Expeditions which led the group containing both Strydom and Eric Ary Arnold, said both climbers became ill very quickly on the descent.

The Dutch climber was assisted down to the South Col camp, the final camp before the summit, where he was given oxygen and medicine but "unexpectedly passed away that evening in his tent," Coster said in a Facebook post.

Strydom decided to turned back from her attempt to reach the summit and was assisted down to the South Col by her husband, veterinarian Robert Gropel. After spending the night there, she walked out of her tent to continue the descent, only to collapse on the Geneva Spur, two hours from Camp 3 where helicopter evacuations are possible.

The expedition leader said Gropel, who himself suffered high altitude pulmonary oedema on the descent, tried unsuccessfully to carry his wife's body down the mountain. He was evacuated by helicopter to Kathmandu on Monday.

May is one of the most popular months to scale Everest before the peak is shrouded by rain, cold and cloud brought on by the monsoon in June.

Good weather over the past two weeks has allowed more than 350 climbers to reach the summit this month from the Nepali side of Everest. Several people have climbed from Tibet.

Among them was 19-year-old Alyssa Azar, who on Saturday became the youngest Australian to reach the summit, and Lhakpa Sherpa, who notched a new record for female climbers with her seventh ascent.