KATHMANDU: Mountaineering experts warned Tuesday that potentially dangerous levels of overcrowding were expected on Mount Everest after four climbers died as “traffic jams” clogged up the world's tallest peak.

Some 200 people will attempt to scale the 8,848-metre (29,029-foot) summit this weekend when the weather is expected to provide the next safe window for the ascent, said Nepal tourism official Gyanendra Shrestha.

There were a similar number of climbers attempting the summit last weekend, he said, with four climbers dying of exhaustion and altitude sickness on Saturday on one of the deadliest-ever days on the peak.

German national Eberhard Schaaf, 61, South Korean Song Won-Bin, 44, 33-year-old Nepali-born Canadian Shriya Shah and Chinese climber Ha Wenyi, 55, were all found dead near the summit.

A Sherpa mountain guide had been reported missing but Shrestha said the information turned out to be false.

Due to an increased numbers of climbers in recent years, there is a bottle-neck every season at the Hillary Step, a rockface near the peak that climbers from the Nepal side have to ascend and descend with the help of ropes.

The climbing season runs from late March to the first week in June but this season's first clear conditions for reaching the peak were on Friday, two weeks later than usual.

The window had closed by Saturday afternoon due to high winds, Shrestha told AFP, leading to a rush of climbers attempting the summit.

“The climbers have to rely on a single rope and the traffic jam there will delay the ascents for hours,” he said by telephone from base camp.

“Some Sherpas who returned have told me that they had to wait for up to three hours. Not moving means that your hands or feet will be frostbitten.

“Then, there is the issue of oxygen... high up, you tend to use more.”Zimba Zangbu Sherpa, president of the Nepal Mountaineering Association, said climbers were increasingly taking unnecessary risks when time was running out or conditions were poor.

“Now there are so many people trying to reach the top, vying for this or that record,” he said.

Some climbers near the peak, most of whom have paid tens of thousands of dollars on the expedition, often ignore the advice to expert guides to turn back, he added.

“In some cases, they don't even heed the suggestions of their Sherpa guides. The Sherpas can't advise them otherwise because their clients will think 'I'm so close to the mountain, why shouldn't I try a bit more?'”

Nearly 4,000 people have climbed Everest since 1953 when Edmund Hillary of New Zealand and Sherpa Tenzing Norgay first scaled it.

More than 200 people have died on the slopes of the giant peak. Two Sherpa climbers were killed on Everest in April, one falling into a crevasse at 5,900 metres and the other succumbing to altitude sickness at base camp.

Elizabeth Hawley, a Nepal-based American former journalist and chronicler of Himalayan expeditions, said overcrowding was being exacerbated by poor preparation.

“The overcrowding has been going on for years... the problem is people who don't belong there getting permits,” she told AFP.

“They think anyone can climb Everest. Anyone can, if they know what they are doing and have proper help and have had the right exercise and are fit. But a lot of people keep going when they should go home.”

Earlier this month Russell Brice of Himalayan Experience, a major operator on Everest, told clients and staff he was cancelling the rest of their season due to the increased danger of falling ice and rock.

The Nepal government said it had issued 325 Everest permits to foreign mountaineers at $10,000 each for 2012.