Eight people who have died descending Mount Everest this week, which is more than the total number of fatalities recorded last year.

Key points: On average between five and ten people die every year climbing Mount Everest

On average between five and ten people die every year climbing Mount Everest Nepal has issued permits to 379 climbers this season with 120 climbing on Thursday alone

Nepal has issued permits to 379 climbers this season with 120 climbing on Thursday alone 18 climbers have died on different Himalayan peaks in Nepal since the start of the season in March

Hiking officials attributed most of the deaths to weakness, exhaustion and delays on the crowded route to the 8,850-metre summit.

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.

Nepal has issued permits to 379 climbers on Mount Everest in the season, which ends this month.

Between five and 10 climbers die on Mount Everest in an average climbing year.

Krishma Poudel, of Nepali mountaineering company Peak Promotion, told NBC 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 8:00am the day before without eating or a proper rest and exposed to that temperature, there's a high risk of being frostbitten and hypothermia."

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Irish climber Kevin Hynes, 56, died in his tent at 7,000 metres on Friday morning, with his family confirming he had felt unwell on his way to the summit and turned back.

Britain's Robin Haynes Fisher, 44, died in the so-called "death zone" known for low levels of oxygen on descent from the summit, Mira Acharya, a tourism department official, said.

Two women from India, Anjali Sharad Kulkarni, 54, from Mumbai, and 49-year-old Kalpana Das, from the eastern state of Odisha, were also among those who died while descending from the summit, which is at 8,848 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."

A total of 18 climbers have died or are missing on different Himalayan peaks in Nepal, seven of them Indians, since the start of the climbing season in March.

Alongside the climbers, a Nepali guide fell sick and died while descending.

ABC/ Wires