AUSTRALIAN mountaineer Lincoln Hall has offered words of encouragement to two climbers stuck on one of the world's deadliest mountains.

A dramatic rescue operation was under way yesterday to save two climbers stranded for three days on a Himalayan peak nicknamed Killer Mountain.

Rescue teams supported by the Pakistani army were attempting to reach the two men, stranded at a height of 7000 metres on Nanga Parbat, the world's ninth highest peak, which gets its grisly nickname from the large number of climbers who have died attempting an ascent.

That tally grew when the stranded men's colleague, renowned Italian climber Karl Unterkircher, perished after falling into a ravine on Friday. A spokesman for the climbers' expedition said his two fellow Italians, Simon Kehrer and Walter Nones, had been unable to find their way back to base camp because heavy rain had opened a number of crevasses.

Mr Hall, who survived a night on his own on Everest, said Nanga Parbat was notorious.

"A fellow mountaineer said to me once: 'Nanga Parbat - that's a good mountain if you want to die.'

"This mountain has a reputation of having a particular bad weather. But there have been incredible accounts of survival - including mine - you should never give up hope."

As part of the operation to save the men, two army helicopters flew in two more Italian climbers who had arrived from Milan to lead the rescue.