ISLAMABAD — The search for three missing climbers will resume early Monday on K2, the world's second highest mountain, Pakistani officials said Sunday.

Onboard the army helicopter was Sajjid Sadpara, the son of the missing Pakistani climber, Ali Sadpara, and the Nepali leader of the winter expedition. Also missing are John Snorri of Iceland and Juan Pablo Mohr of Chile.

The three lost contact with base camp late Friday and were reported missing Saturday after their support team stopped receiving communications from them during their ascent of the 8,611-meter (28,250-foot) high K2 mountain, sometimes referred to as "killer mountain."

The military said a ground search has also been initiated from the K2 base camp.

Karrar Haideri, a top official with the Alpine Club of Pakistan, said army helicopters will resume the search that began a day earlier.

A military statement elaborating the day search and rescue operation said despite "extremely challenging conditions," the army helicopters searched Abruzzi Spur and other routes but no trace of the missing climbers so far.

It said the success of the search efforts depend on the weather. Choppers flew up to the limit of 7,800 meters over the K2.

K2, located in the Karakorum mountain range, is one of the most dangerous climbs. Last month, team of 10 Nepalese climbers made history by scaling the K2 for the first time in winter.

"The base camp received no signals from Sadpara and his foreign companions after 8,000 meters ... A search is on and let's pray for their safe return home," Haideri told The Associated Press.

Pakistan's foreign ministry issued a statement saying Iceland's foreign minister, Gudlaugur Thór Thórdarson, spoke to his Pakistani counterpart, Shah Mahmood Qureshi, by telephone. Qureshi assured him that Pakistan would spare no effort in the search for the missing mountaineers.

Sadpara and his team left the base camp on Feb. 3, a month after their first attempt to scale the mountain failed because of weather conditions.

Although Mount Everest is 237 meters (777 feet) taller than K2, the K2 mountain is much farther north on the border with China and subject to worse weather conditions, according to mountaineering experts. They say a winter climb is particularly dangerous because of the unpredictable and rapid change in weather conditions.

Winter winds on K2 can blow at more than 200 kph (125 mph) and temperatures can drop to minus 60 degrees Celsius (minus 76 Fahrenheit). In one of the deadliest mountaineering accidents ever, 11 climbers died in a single day trying to scale K2 in 2008.

Haideri said Sadpara's son, Sajid, had returned to the base camp safely after his oxygen regulator malfunctioned at 8,000 meters.

Chhang Dawa Sherpa, who heads the Seven Summit Treks expedition company and also was the leader of winter expedition, tweeted that two army helicopters along with Saijd Sadpara, Elia and himself found no trace during their two days of aerial searches.

Sherpa said on Saturday around noon, Ali's son Sajid reported that they were together and in good shape to head toward the summit. But due to a problem with his oxygen regulator Sajid had to return from their location, known as Bottle Neck. Sajid waited for them for more than 20 hours with the belief that they were heading to the summit and would return. With no sign of them, Sajid descended.

Sajid Sadpara said on Twitter "It was around 11 AM they were going up and I am sure they have done the summit and on descend they might have faced (a) problem."

Haideri, the Alpine club official, was hopeful that Sadpara's company will help his other companions survive rough conditions.

He noted Sadpara's experience as a mountaineer who has climbed the world's eight highest mountains, including the highest, Mount Everest in the Himalayas, and was attempting to climb K2 in winter.

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Asim Tanveer contributed to this story from Multan, Pakistan.