Kathmandu  - Veteran Swiss mountaineer Uwe Gianni Goltz died on his way to the summit of Mount Everest, officials said Friday.

Goltz, 44, was attempting to climb the 8,848-metre-high Mt Everest without the aid of artificial oxygen, which is needed at high altitude, Nepal Mountaineering Association said.

However, the exact cause for Goltz's death and when it happened remained unclear.

Goltz previously climbed Cho Oyu, Manasulu and Dhaulagiri in the Nepalese Himalayas as well as other peaks elsewhere.

Goltz was from Val Maggia in southern Switzerland.

Separately, Nepalese and international mountaineers were attempting to rescue a Spanish climber high up on the 8,091 metre high Mt Annapurna, about 200 kilometres north-west of the Nepalese capital Kathmandu.

Climber Inaki Ocho, who was suffering from altitude sickness, frostbite and chest infection, was stranded at 7,400 metres on the mountain and efforts were being made to bring him down to base camp, said Nima Nuru Sherpa, managing director of the Cho-Oyu Trekking Pvt Ltd, which handled the expedition, said.

"Plans are to airlift the sick climber to Kathmandu once he is brought down to the base camp," Nima said.

Meanwhile, more climbers reached the summit of the world's highest peak Friday, bringing the total number of climbers to reach the summit this season to at least 140.

Everest News website said six members of IMG Everest Expedition reached the summit Friday morning.

They included Three Nepalese high altitude Sherpa guides and climbers from the United States, Poland and Canada.

The website said Mingma Tenzing Sherpa reached the summit for the fourth time while it was the second summit for Tsewang Lendu Sherpa.

On Thursday, over 80 climbers reached the summit of Everest as expeditions scramble to get their climbers on the highest point on earth.

The Spring climbing season concludes at the end of May. The season was cut short by a 10-day ban imposed by the Nepalese government coinciding with the Chinese attempt to take the Olympic torch to the summit of Everest.

The Nepalese government says it has given permission to 30 expeditions to scale Everest during the Spring season this year. (dpa)