UPDATE 3-Frostbitten Italian survivor reaches K2 base camp

(Adds Italian climber's quotes, background)

By Kamran Haider

ISLAMABAD, Aug 5 (Reuters) - Hobbling on frostbitten feet, an Italian climber walked down to K2 base camp on Tuesday after heavy mists ruled out an airlift for the last survivor of the worst disaster on the world's second-highest mountain.

"I'm at base camp. I'm truly happy, to be here finally and to be alive," 37-year-old Italian climber Marco Confortola was quoted as saying after speaking by satellite telephone to the Italian mountaineering website www.montagna.tv.

"I now realise that they're all dead, they're all dead."

Eleven climbers from Europe, South Korea and Pakistan died, mostly as a result of an ice fall during their descent after summitting the 8,611 metre (28,240 foot) peak late on Friday.

Some fell to their deaths, others froze, and some went missing in the freezing thin air above 8,000 metres, known to mountaineers as the "Death Zone" as the body and brain begin shutting down due to lack of oxygen.

Confortola refused to give in, and a rescue party made up of an American climber and Pakistani high-altitude porters raced up the steep flanks of the towering pyramid of rock and ice on Monday to help bring him down.

They bivouaced together on Monday, Confortola's fourth night at high altitude on the mountain since Friday's calamity, and descended to a camp at 6,000 metres in the morning.