A record 274 climbers have reached the summit of Mount Everest from the Nepalese side in a single day after a spring season that started late because of the threat of ice fall on the normal tourist route.

The climbers took advantage of the clear weather on Wednesday, said Rishi Ram Bhandari, of the Expedition Operators Association Nepal.

“This is the highest ​number of climbers in a single day so far,” Bhandari told Reuters, referring to the Nepali record, adding that the number could rise as some climbers who had summited might not have informed the base camp yet.

All but one of the climbers reached the summit assisted by Sherpa guides and using supplementary bottled oxygen. The Ecuadorian climber Marcelo Segovia summited while climbing independently and without oxygen.

Mountaineering experts often criticise Nepal for allowing large numbers ​of climbers on the mountain, ​which sometimes leads to risky jams or long queues in the “death zone” area below the summit, where the level of natural oxygen is below what is required for human survival.

The large convergence on a single day appears to have occurred as climbers who had been waiting in higher camps for better wind conditions were joined by climbers from lower camps, with some reporting queues and a slow pace of ascent.

The 8,849-metre (29,032ft) peak can be scaled from either the southern side in Nepal or the northern face in China’s Tibet. On 22 May 2019, Nepal’s side had 223 and the Chinese side had 113 climbers on the summit. Chinese authorities, however, have closed the route this year.

This week, the veteran mountain guide Kami Rita Sherpa scaled the peak for the 32nd time, breaking his own record for the most summits of Everest. His closest rival, Pasang Dawa Sherpa, scaled the peak for the 30th time this week. Also, Lhakpa Sherpa scaled Everest for the 11th time, topping her own record for the most summits by a female climber.

This year’s Everest climbing season began late because of the risk from a huge serac, glacial ice cliff, hanging over the key route to the summit.

There are 494 climbers and an equal number of Sherpa guides expected to attempt to scale the mountain by the end of May, when the climbing season on the peak ends.

Thousands of people have climbed Everest since it was first scaled on 29 May 1953 by Sherpa Tenzing Norgay and the New Zealander Edmund Hillary.

A Department of Tourism official, Himal Gautam, said he had ‌received preliminary ⁠information that more than 250 people climbed the peak on Wednesday.

“We wait for climbers to return, give us photographs and other evidence to prove their ascents and provide them with climbing certificates,” Gautam told Reuters. “Only then we will be able to confirm the numbers.”

Nepal has issued 494 permits to climb Everest this year, each costing $15,000.

Reuters and AP contributed to this article