Pakistani officials say pro-government tribesmen have killed 23 militants during clashes in the volatile northwest.
Officials say Tuesday's fighting took place in the Mohmand tribal region, which lies along the country's border with Afghanistan.
Pakistan's government has encouraged tribesmen in the area to form local militias, known as lashkars, to combat Taliban militants blamed for attacks in Pakistan and Afghanistan.
In other violence, militants ambushed a NATO oil tanker in the Khyber tribal agency, killing two civilians and wounding three others. Local officials say the attackers opened fire on the tanker and ignited it. They then fled after security forces returned fire.
Pakistan's military has been fighting Taliban militants throughout the northwest for more than two months, forcing some two million people to flee homes in the conflict areas.
While the government has called the Swat campaign successful, clashes with Taliban fighters in the region continue.
In the last 24 hours, the military said its forces killed nine suspected militants and detained eight others. Despite the violence, the Pakistani government began transporting people back to their homes this week.
On Monday, about 200 families left two refugee camps near Peshawar on government buses and army trucks. Others are refusing to return home, citing security concerns and saying they have not received essential food and financial aid promised by the government.
Pakistani Prime Minister Yousuf Raza Gilani estimated the government needs some $2.6 billion for reconstruction and rehabilitation projects in the greater Swat Valley region.