The authorities did not say where he was from in the United States (File)

An American climber died on the descent from the summit of Mount Everest on Monday, a Nepalese official said, taking the number of dead or missing mountaineers on the world's highest mountain to nine on the Nepali side during the current climbing season.

Christopher John Kulish, 61, scaled the 8,850 metre (29,035 feet) peak from the normal Southeast Ridge route in the morning but died suddenly at South Col after descending from the summit, Mira Acharya, a Nepal tourism department official said.

The authorities did not say where he was from in the United States. The cause of his death was unclear.

Most of the deaths on Everest this year have been attributed to exhaustion and tiredness, exacerbated because a crowded route to and from the summit has led to delays. The short climbing season ends this month.

The route, also called the South Col route, was pioneered by New Zealander Sir Edmund Hillary and Nepalese Sherpa Tenzing Norgay in 1953.

About 5,000 people have scaled the Everest summit so far and about 300 have died on its slopes.

Two climbers are also confirmed dead on the Tibetan side of Mount Everest this climbing season.

A record 381 climbers had been permitted to scale the summit from the Nepali side this season. About 130 others were tackling Everest from the mountain's northern side in Tibet.