Two Polish climbers are missing after making the first ever winter ascent of the 12th highest mountain in the Himalayas called Broad Peak, the expedition leader told media Wednesday.
Tomasz Kowalski, 27, and Maciej Berbeka, 51, were among four Poles who summited the 8,051-metre (26,414-foot) peak Tuesday.
"We lost phone contact with them at 0300 GMT (Wednesday)," expedition leader Krzysztof Wielicki told Polish media.
"We're afraid they may have fallen into a crevice," expedition spokesman Artur Hajzer said.
The other two climbers who made the ascent, Adam Bielecki, 29, and Artur Malek, 33, had descended to a camp at 7,400 metres above sea level, Hajzer said.
The group had split before the final phase of the ascent.
A search team had been sent back up the mountain but had failed to find Kowalski, 27, and Berbeka, 51, he said.
"Three Pakistanis set out to help on Wednesday morning. One of them climbed to some 7,700 metres but did not find a trace of the climbers," he said.
Hajzer said the rescue mission was interrupted as night fell.
Broad Peak, on the border between China and Pakistan, is the twelfth highest in the Himalayas, the world's highest mountain range. At 8,848 metres, Mount Everest is the highest.
The latest Polish ascent means that only two of the range's 14 peaks higher than 8,000 metres above sea level have not been climbed in winter -- Nanga Parbat (8,126 metres) and K2 (8,611 metres).
Winter ascents in the Himalayas have become a speciality among Polish climbers as mountaineers from the central European country have been the first on 10 of the 14 peaks in winter, Polish media say.