Nepal has issued a record 454 permits to climb Mount Everest this spring, officials said Monday, four years after at least four deaths on the world's highest peak were blamed on overcrowding.

"This is the highest number of permits the department has issued to summit Mount Everest," Bigyan Koirala from the tourism department told AFP, adding that numbers could rise further.

As most of these mountaineers will attempt to summit Everest with the help of a Nepali guide, over 900 climbers will be heading for the summit in the next few weeks.

This could cause heavy traffic and bottlenecks en route to the summit if there is a shorter window period to reach it because of unfavourable weather.

In 2019, a massive queue on Everest forced teams to wait hours in freezing temperatures, lowering depleted oxygen levels that can lead to sickness and exhaustion.

At least four of 11 deaths that year were blamed on overcrowding.

The highest number of climbers receiving permits this season were from China (96), followed by the United States (87).

Ang Tshering Sherpa, former president of the Nepal Mountaineering Association, told AFP that the high numbers this season were the result of many climbers being unable to travel to Nepal in recent years due to disruption caused by the pandemic.

In addition, new rules on the Chinese side of Everest -- requiring climbers to have scaled one other 8,000-metre peak first -- were sending more Chinese to Nepal.

A team of professional mountaineers is currently preparing the route up to Everest and has already fixed rope up to Camp IV at 7,924 metres (25,997 feet).

Sherpa said recent snowfall has heightened the risk of avalanches on the mountains.

"Normally, it's during the winter when there should have been a snowfall. But there was snowfall recently during the spring. The fresh snow remains soft which increases the risk of avalanche," said Sherpa.

Three Nepali climbers went missing on Everest while crossing the treacherous Khumbu Icefall on April 12. Authorities called off the rescue after concluding that it was not possible to retrieve their bodies from a deep crevasse.

Nepal is home to eight of the world's 10 highest peaks and foreign climbers who flock to its mountains are a major source of revenue for the country.

The government has collected a total of $4.86 million from the Everest permits, charging $11,000 per foreign climber.