The last survivor of the deadliest mountaineering disaster atop the world's second highest peak K2 was rescued by a helicopter Wednesday.

Italian climber Marco Confortola, 37, arrived at base camp Tuesday after surviving four nights at high altitude with severe frostbite, but thick clouds forced him to stay overnight.

Confortola and three members of his support team were taken from the base camp and on their way Wednesday to a nearby town, said Maj. Farooq Feroz, a spokesman for the Pakistani army.

Confortola was among as many as 30 mountaineers who began trekking up K2 on Friday. Just below the 8,610-metre summit, an avalanche swept away some climbers and left some stranded, causing them to freeze to death.

Eleven people are missing and presumed dead, including three South Koreans, two Nepalis, two Pakistanis, and mountaineers from France, Ireland, Serbia and Norway.

Confortola's toes were blackened by frostbite, but he was otherwise in good condition, said the group's spokeswoman, Francesca Steffanoni.

"I am fine; luckily I'm made of stern stuff," Confortola told the Everest-K2-CNR, an Italian-based high-altitude scientific research group, during a phone call from the camp.

"The only problem is that my feet hurt. I spent seven days on that mountain. It was hard. It was terrible."

Islamabad vows to probe incident

The incident is the deadliest in memory, surpassing the seven climbers killed on K2 during a fierce storm in 1995.

K2 straddles Pakistan and China in the Karakoram range, and is seen as more challenging than Mount Everest, the world's highest peak, as it is steeper and prone to avalanches and storms.

Confortola said the expedition was undermined by inexperience and low-quality equipment, including ropes and spikes that easily broke. His comments echoed those made by a Dutch survivor.

He told Everest-K2-CNR that he felt helpless when he and others made a futile attempt to rescue three Koreans dangling from a rope. He said he was too weak and had to give up.

Government officials in Islamabad have promised to investigate the tragedy.

About 280 people have reached K2's summit since 1954, when it was first done by Italians Achille Compagnoni and Lino Lacedell.

Dozens of deaths have been recorded since 1939. Most have occurred during the descent.

With files from the Associated Press