An experienced mountaineer has described the “death, carnage and chaos” at the top of Mount Everest as climbers pushed past bodies to reach the world’s highest summit.

The death toll on the mountain grew to 11 in the past day after an American doctor was killed while descending from the peak. It emerged also that an Australian climber was discovered unconscious but had survived after being transported downhill on the back of a yak.

Elia Saikaly, a film-maker, reached Hillary Step, the final stage before the summit, on the morning of 23 May, where he said the sunrise revealed the lifeless body of another climber. With little choice at that altitude but to keep moving, his team – including Joyce Azzam, the first Lebanese woman to climb the world’s “Seven Summits” – made it to the peak a short time later.

“I cannot believe what I saw up there,” Saikaly said of the last hours of his climb in a post on Instagram. “Death. Carnage. Chaos. Lineups. Dead bodies on the route and in tents at camp 4. People who I tried to turn back who ended up dying. People being dragged down. Walking over bodies. Everything you read in the sensational headlines all played out on our summit night.”

This year’s Everest climbing season is so far the fourth deadliest on record, with mountaineers blaming poor weather, inexperienced climbers and a record number of permits issued by the Nepalese government, which, along with a rule that every climber has to be accompanied by a sherpa, led to there being more than 820 people trying to reach the summit.

“There were 200-plus climbers making their way to the summit,” Saikaly told the Guardian of his ascent. “I came across a deceased climber … that person’s body was fixed to an anchor point between two safety lines and every single person that was climbing towards the summit had to step over that human being.

Facebook Twitter Pinterest Mount Everest peak. Photograph: Niranjan Shrestha/AP

“It’s difficult for people at sea-level, who are not mountaineers, who have never been above 8,000 metres, to understand that particular scenario. When you are on Everest and you’re in the death zone and you can barely think … it becomes a very complicated situation and you realise in your mind that your fate could be the same. And with a line-up pushing you up the mountain there is nothing you can do. You really have no choice but to carry on.”

The scene arising from the restricted chance to climb affecting large numbers of mountaineers was captured and widely circulated in a picture taken by Nirmal Pujra on the morning of 23 May. It showed more than 100 climbers waiting, some for up to 12 hours, for a turn to make the summit. More than 200 people reached the top of the 8,848-metre peak that day.

Chad Gaston, another climber who successfully reached the peak, described the difficulty of passing incapacitated people as he ascended, including a man wrapped “like a mummy with ropes tied to him”. He wrote: “The climber was non-responsive and I never saw him open his eyes.”

Further up he saw a man “holding his chest and bent over”. Gaston said: “I waited for a moment and after he didn’t move, I approached him. He said he was having a hard time breathing, even though I saw his oxygen mask was fine. He was in really bad shape, pale faced, not coherent and shaking … I’m sad to say I heard he passed, that night on the mountain.”

Ten more people have died in the past month while trying to climb other Himalayan mountains, bringing the overall death toll to 21.

An Australian climber was found unconscious on the peak and was identified on Tuesday as Gilian Lee. The Canberra man, who survived the 2015 avalanche on the mountain, was attempting it for the fourth time without the use of supplementary oxygen when he was discovered on Wednesday by a Nepali team, said Mingma Sherpa, chairman of Seven Summit Treks. A yak carried Lee about 1,000 metres down the mountain to a vehicle stationed at about 5,600 metres. He was flown to hospital in Kathmandu and placed in intensive care.

Lee wrote of his experience in 2015 when the mountain was hit by an avalanche, on 25 April, triggered by a 7.8-magnitude earthquake. “I felt the ground shake, around 20cm lateral movement that unbalanced me inside the tent. We could hear an avalanche starting and it kept building … The biggest wall of vertical snow (guess 50m high of white fluff) was heading right towards us uphill.”

Facebook Twitter Pinterest Ameesha Chauhan, from India, who survived dangerous overcrowding on Mount Everest, in hospital in Kathmandu on Tuesday. Photograph: Niranjan Shrestha/AP

The deaths have restarted a debate over whether better regulation is needed for Everest, especially on the Nepalese side, where 381 climbing permits were issued this year.

The number of people seeking to scale Everest has exploded in recent years, driven by surges in climbers from India and China. Dozens of cut-rate climbing companies have also sprung up in the past 10 years, with some accused of cutting corners or lowering requirements for clients’ fitness and experience levels.

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Alan Arnette, an experienced climber and chronicler of the mountain, said that climbers waiting for hours on overcrowded peaks – putting pressure on oxygen supplies – was probably responsible for five of the 21 deaths so far this season; the remainder could have been due to poor training, inexperience, hidden health issues and inadequate support from guides.

“It is mainly due to the carelessness of climbers,” said a sherpa. “The government should ensure that prospective climbers should have prior experience of climbing peaks before trying to conquer the mighty Mount Everest.”

Saikaly said it may have been his last ascent of the mountain. “I was really turned off this year and I’m just worried,” he said. “I’m really worried for the years ahead of us and what the state of the mountain will be and how much more lives will be lost.

“I’m not sure if I’ll head back. I certainly know that as I was climbing up I was certainly doubting whether or not I would ever return.”