Min Bahadur Sherchan died at Everest base camp on Saturday and his body was airlifted to Kathmandu. 

"Doctors said that he died of natural causes. There was water build-up in his lungs because of altitude sickness," Shiv Raj Thapa of Summit Nepal Trekking told AFP after an autopsy.

Sherchan was resting at the base camp and waiting for the weather window to summit in a single attempt, skipping the usual multiple acclimatization rotations because of his age. 

In this photograph taken on February 10, 2017, Nepalese mountaineer Min Bahadur Sherchan shows off his 2008 Guinness World Record certificate for being the oldest person to summit Mount Everest -- a record that was later broken in 2013 -- during an interview with AFP in Kathmandu. An 85-year-old former Gurkha is making a bid to reclaim his title as the world's oldest person to summit Mount Everest. A Guinness World Record certificate hangs proudly in Min Bahadur Sherchan's Kathmandu home and by the end of this year's spring climbing season he hopes to have a second one hanging next to it.(AFP/Prakash Mathema)

He was on a bid to reclaim a title that he lost to Japanese mountaineer Yuichiro Miura in 2013.

The former soldier became the oldest person to summit Everest in 2008 when he was 76, but he lost the record five years later when Miura reached the 8,848-metre peak at the age of 80.

Speaking to AFP earlier this year, the slightly hard of hearing grandfather said he just wanted to prove to himself that he could still make it to the top of the world.

Read also: At 85, Nepali aims to regain title of oldest Everest climber

"My aim is not to break anybody's record, this is not a personal competition between individuals. I wish to break my own record," Sherchan had said in February.

Sherchan's death is the second fatality of the spring climbing season on Everest, which runs from late April to the end of May.

Officials carry the body of Nepalese mountaineer Min Bahadur Sherchan, airlifted from Everest Base Camp to a hospital in Kathmandu, on May 7, 2017. An 85-year-old ex-Gurkha who was attempting to reclaim his title as the world's oldest person to summit Mount Everest died at base camp on May 6.(AFP/Bikash Karki)

Experienced Swiss climber Ueli Steck died last month when he fell from a steep ridge during an acclimatization exercise.

Nearly 750 people will this year attempt to summit the world's highest mountain during the narrow window of good weather that usually falls in mid-May.

Hundreds of climbers have been on Everest for weeks to acclimatize before making a bid for the top.

This year is particularly crowded as it is the last chance for climbers who were forced off the mountain by the devastating 2015 earthquake to use their extended permits. This has raised concerns about dangerous traffic jams on the mountain.

Mountaineering is a major revenue earner for impoverished Nepal, home to eight of the world's 14 peaks over 8,000 meters.