KATHMANDU, May 13 (AFP) - Two climbers from the United States and Switzerland have died on Mount Everest, the first fatalities of this year's season, expedition organisers in Nepal said on Thursday (May 13).

On average, about five climbers die every year on the world's highest peak.

But in recent seasons, Everest has seen a surge in the number of climbers, leading to overcrowding that has been blamed for multiple deaths.

"Two climbers passed away on Wednesday," Mingma Sherpa of Seven Summit Treks told AFP.

Swiss climber Abdul Waraich, 40, died near the summit after reaching the top and suffering exhaustion, said Chhang Dawa Sherpa from the same organisation.

"We sent two additional Sherpas with oxygen and foods, unfortunately Sherpas couldn't save him," he said on Instagram.

American Puwei Liu, 55, reached the Hillary Step but was helped back down after he suffered snow blindness and exhaustion, organisers said.

He was able to reach Camp 4, "before he suddenly passed away" late on Wednesday, Chhang Dawa Sherpa said.

Eleven people died climbing the world's highest peak in 2019, with four deaths blamed on overcrowding.

On one day, 354 people were lined up to reach the top from Nepal's southern side and Tibet's northern approach.

To ease the crowding, Nepal's tourism ministry announced rules capping the number of people who can summit the mountain per window of suitable weather.

Expedition organisers have been told to send teams up the peak strictly in accordance with permit numbers or limit the number of climbers going up at one time.