KATHMANDU, Nepal — A Swiss climber acclaimed for his rapid ascents — including scaling dozens of peaks in the Alps in a little more than two months — died Sunday in a mountaineering accident near Mount Everest in Nepal, expedition organizers said.

Ueli Steck died at Camp 1 of Mount Nuptse, Mingma Sherpa of Seven Summit Treks said

Steck’s family said the exact circumstances of his death were still unclear.

“The family is infinitely sad and asks that the media refrain from speculating about his death out of respect and consideration for Ueli,” it said in a statement on Steck’s website. “As soon as reliable information about Ueli Steck’s death becomes available, the media will be informed.”

Steck was planning to climb 29,035-foot Mount Everest and nearby Mount Lhotse next month.

He was the first casualty in the spring mountaineering season in Nepal that began in March and will end in May. Hundreds of foreign climbers are in the Himalayan region to attempt to climb peaks when weather is most favorable.

Steck, 40, was best known for his speed-climbing, including setting several records for ascending the north face of Eiger, a classic peak in the Bernese Alps that he climbed in two hours and 47 minutes without using a rope.