A British man has died minutes after summiting Mount Everest, bringing to 10 the total death toll this season on the world's highest peak.
Robin Haynes Fisher, 44, reportedly fell ill while descending from the summit.
Nepal is facing scrutiny for issuing a record 381 permits, at $NZ16,685 each, for this year's spring season.
There have been reports of overcrowding and queuing climbers near the summit. This week a photograph showing the tailbacks on Everest has been shared widely on social media.
Mr Fisher made it to Everest's summit on Saturday morning but collapsed and died only 150m down from the peak, his expedition company confirmed.
Despite efforts to wake him and to give him oxygen and water, the climber remained unresponsive and guides radioed their base camp to confirm he had died just 45 minutes after Mr Fisher had stood atop the mountain.
Reports said one of his Sherpa guides had also complained of feeling ill, and was taken to a lower camp.
A statement from the British climber's family paid tribute to an "aspirational adventurer" who "lived life to the full".
"We are deeply saddened by his loss as he still had so many more adventures and dreams to fulfil," the statement added. "Everyone who ever met him in any capacity will always remember the positive impact he had on their lives."
This year's deaths are more than the total fatalities over the whole of last year.
More than 120 climbers scaled Everest on Thursday, but some of them were caught in the crowd of people on the slopes, leading to exhaustion, dehydration and death.
Former British soldier Nirmal Purja shared a photograph of the long queue to the summit on Twitter, showing exactly how crowded the world's tallest mountain can become during the short climbing season.
'Every minute counts' in lethal environment
Krishma Poudel, who works with Nepali mountaineering company Peak Promotion, told NBC that the congestion on the peak could be lethal.
"Before you reach the summit, you have to wait and every minute counts at the height," she said.
"You've been walking since 8am the day before without eating or a proper rest and exposed to that temperature, there's a high risk of being frostbitten and hypothermia."
Irish climber Kevin Hynes, 56, died in his tent at 7000 metres on Friday morning, with his family confirming he had felt unwell on his way to the summit and turned back.
Two women from India, Anjali Sharad Kulkarni, 54, from Mumbai, and 49-year-old Kalpana Das, from the eastern state of Odisha, were among those who died while descending from the summit, which is at 8848 metres.
Lhakpa Sherpa, from tour agency Arun Treks and Expeditions, said Ms Kulkarni died of weakness while coming down to Camp IV on the South Col of Everest.
The other Indian climber who died was 27-year-old Nihal Ashpak Bagwan, from Pune.
"Bagwan died of dehydration, exhaustion and tiredness after being caught in the jam of climbers," Keshab Paudel from Peak Promotion said. "We don't know for how long the jam lasted nor how many climbers were clogged by a single line near the summit."
- BBC / ABC