Aidin Bazurgi, Mujtaba Jarahi and Pouya Kaywan were stuck at 7800 metres on Wednesday while descending the 8047-metre 'Broad Peak' in the Karakoram area in Pakistan's Gilgit-Baltistan region, Karar Haidri of Alpine Club of Pakistan told PTI.
They contacted the local authorities for help and rescue teams were sent but they could not find them due to bad weather, he said.
The contact with the three climbers was lost on Saturday and since then all efforts to locate them have failed, Haidri said.
The Iranians led by Bazurgi left the base camp on July 13 and made a daring attempt to scale the peak from a different route on the south-west side.
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They accomplished their mission when they reached the top of the peak three days later.
However, they were stuck while coming down and got lost.
This was the third major tragic incident involving trekkers in Pakistan recently.
Last month militants in security forces uniform attacked a team of foreign climbers and killed nine of them.