The army said on Thursday that 15,000 soldiers and officers were involved in the operation around the regional center of Mingora in the Swat valley. The military has blocked-off the Taliban-controlled town, where there are about 4,000 militants.
The siege was lifted temporarily on Friday to allow local residents to leave, with an estimated 834,000 people having registered at UN refugee centers this month. The United Nations has said the mass exodus could be the region's greatest humanitarian disaster in recent years.
It said many of the displaced persons have no shelter and urgently require food and essential goods from the international community.
The operation against the Taliban in the Swat, Buner and Lower Dir districts began on April 26. Around 750 militants have been killed, as well as 33 military personnel, regional media reported.
