"New Zealander Martin Walter Schmidt, 53 and Denali Walter Schmidt, 25, father and son in relation, are reported missing on July 28 afternoon from Camp III at 7,400 metres on the world's second highest mountain, 8,611-metre-high K-2," Alpine Club of Pakistan said in a late night statement.
Contact with the Kiwi mountaineers was lost on the afternoon of July 26 with the Base Camp group leader Australian Christopher Warner.
The Sherpa who reached the camp this afternoon reported no signs of the mountaineers in their tent which appeared damaged due to an avalanche.
He found mountaineers' ice axes and crampons lying intact.
"It is assumed that both the climbers might have been swept down by an avalanche," said the statement.
The search is continuing with more help from Base Camp tomorrow with survey of Advance Base Camp area.
Both climbers had earlier scaled the 8,047-metre-high Broad Peak just 14 days ago and so were well acclimatised for the climb on K-2.
Last month, 10 foreign climbers were shot dead by pro-Taliban militants.
This month already three Iranian and three Spanish climbers who went missing have been declared dead.
