Tourism officials, however, rejected the notion that the summit had become deadlier because of overcrowding related to the large number of climbers receiving permits. In recent years, concerns have also grown about how loosely regulated the expeditions are, with some organizers using old equipment, particularly oxygen cylinders, to maximize profit.
Danduraj Ghimire, director general of the tourism department, attributed the casualties to two factors: a delay because of the cyclone effect on Everest in fixing the rope that the climbers use to ascend and descend, and the fact that many of the climbers want to ascend Everest only on the best climbing day.
“It’s not because of traffic jam,” Mr. Ghimire said. “The number of climbers was a bit high this year, and most climbers wanted to climb within a short weather window.”
Among the climbers who have died are four Indians and one each from the United States, Ireland and Britain. Most of the deaths occurred at higher camps on Wednesday and Thursday, when Everest witnessed the worst traffic jam.
The American has been identified as Donald Cash of Sandy, Utah, who was completing his goal of climbing the highest mountains on all seven continents. Official records showed Mr. Cash fainted twice on Wednesday at about 28,779 feet. His family believes he had a heart attack.
As the number of climbers increased this year, expedition companies and government officials divided them into groups so that they could climb Everest within the short monsoon window left for climbers.
Based on a forecast analysis by liaison officials at the Everest Base Camp, 122 climbers were scheduled to summit Everest on May 21, 297 on May 22 and 172 on May 23 — the three days when the weather would be most conducive.
Tourism officials, however, said some of the climbers who arrived before these dates had also been stuck, and they added to the number of people scheduled for these dates.
Ang Tshering Sherpa, former president of Nepal Mountaineering Association, said that in addition to the weather fluctuation, the government was to be blamed for delaying by a week permission for a helicopter flight to fix the rope at the highest peak.
“These incidents could be averted if the rope was fixed on time,” he said.