The last survivor from the worst disaster in the history of the K2 mountain hobbled into base camp yesterday afternoon, to be told that 11 fellow climbers had died.

It is hoped that Italian Marco Confortola may be able to shed some light on the fate of Irish climber Gerard McDonnell who was confirmed dead by Pakistani authorities earlier this week.

"I'm at base camp. I'm truly happy to be here finally and to be alive," Mr Confortola (37) said yesterday after spending an incredible four days exposed on the slopes of the mountain following the ice avalanche in the early hours of Saturday morning.

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

The 11 climbers who died were from Europe, South Korea and Pakistan. Many perished as a result of an ice fall during their descent after summitting the 8,611 metre peak late last 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.

But Mr Confortola displayed remarkable strength of will as he battled frostbite and a lack of oxygen to stay alive alone on the mountain over the weekend before a rescue party reached him on Monday.

The group stayed together on Monday night before descending to a camp at 6,000 metres yesterday.

Attempts to pluck Mr Confortola off the mountain using a helicopter were hit by poor visibility.

"Now I just want to take off my shoes, since my feet are hurting something awful," the Italian said as he was seen by a doctor at base camp.

There were suggestions yesterday that Mr Confortola may have spent Saturday night huddled together in the snow with Mr McDonnell and team leader Wilco Van Rooijen after the river of ice had swept a number of climbers off the mountain and left the rest stranded above.

It is now expected that Mr McDonnell's partner Annie, brother JJ and mountaineer Pat Falvey will fly out to Islamabad in an effort to get some answers.

"We hope to arrange a meeting with Wilco [Van Rooijen] on Sunday and we have a list of questions that we want to ask and hopefully we'll get a full debriefing," Mr Falvey said.

Mr Falvey added that there would be a memorial service for Mr McDonnell in Kilcornan, Limerick on August 17 and that a book of condolence for the climber could be accessed through www.patfalvey.com .

"His mother won't have him back but we're trying to give her the feeling of love and respect that people in Ireland and all over the world had for Ger," he said.