A rescue mission to pluck the surviving members of an Italian team from the Himalayan mountain of Nanga Parbat ran into complications on Friday after it became uncertain whether helicopters could reach them.
Walter Nones, 36, and Simon Kehrer, 29, have been on the mountain face since top Italian mountaineer and teammate Karl Unterkircher fell to his death on Wednesday.
The three-man team had been trying to open a new route to the top of the Himalayan giant.
Earlier on Friday rescuers said they thought the men were waiting for rescue in a tent spotted near the site of Unterkircher's accident, but it is now thought the tent is pitched further up where air is too thin for helicopters to fly.
''Things are getting more complicated and the situation is extremely dangerous,'' said Italy's greatest living mountaineer Reinhold Messner, who has been in touch with the Italian team's base camp.
''It's extremely difficult to work out the exact height of the tent because of the clouds, but it seems it has been pitched at between 6,500 and 7,000 metres and not at 6,400 metres as we first thought.
''That's too high for a helicopter to intervene,'' he explained.
Messner said it was ''impossible'' for the climbers to retrace their steps down the tricky Rakhiot face of the mountain, and their only options were to wait for help or to continue their ascent before coming down the standard route on the other side of the mountain.
''It's very likely that Nones and Kehrer continued the ascent after the accident and are trying to reach the Diamir side of Nanga Parbat, where they hope to find the tents and ropes of another expedition''.
Staff at base camp have been unable to reach the two men on their satellite phone since the accident, when the climbers said they were running out of battery power.
''We have to hope the pair heard the sound of the helicopter during the reconnaissance flight. That should give them hope,'' said Messner, whose younger brother Guenther died on Nanga Parbat in 1970.
''At this point Simon and Walter need to go back to where the accident took place, where the helicopters will be able to hoist them aboard,'' he added.
Two rescue helicopters belonging to the Pakistan army and coordinated by the Italian rescue team are set to fly up the mountain face on Saturday morning at dawn as soon as cloud cover has cleared.
Nanga Parbat, whose name in Urdu is 'Naked Mountain', is the world's ninth highest mountain.
It has been nicknamed the Killer Mountain because of the difficulties it poses.
Messner paid tribute to Unterkircher, who had successfully scaled Everest and K2, as the ''new star of mountain climbing'' following Wednesday's tragedy.
