At least 13 Nepalese guides preparing routes up the Qomolangma, known as Mount Everest in the West, for commercial climbers were killed on Friday by an avalanche in the most deadly mountaineering accident ever on the world's highest peak, officials and rescuers say.

The men were part of a large party of Sherpas carrying tents, food and ropes who headed out in bright sunshine early in the morning ahead of the main climbing season, which starts later this month.

The avalanche occurred at around 6:45 am local time at an altitude of about 5,800 meters in an area known as the "popcorn field", which lies on the route into the treacherous Khumbu Icefall.

An avalanche hit Khubuche area near Camp 1 of Mount Everest at around 5:30 am local time.

"The bodies of the deceased have been brought down to the Everest base camp by chopper," Lamakaji Sherpa, chief of the Sagarmatha Pollution Control Committee, told Xinhua by phone.

Eight have been rescued and brought to the base camp for treatment, while the Tourism Ministry has already sent three helicopters to the site to support the rescue operation.

As more than 10 people remained missing, the authorities feared the death toll might rise. So far, none of the foreigners have been reported dead.

The previous worst accident occurred in 1996 when eight people were killed over a two-day period during a rogue storm while attempting to climb the mountain.

AFP-Xinhua