Pakistan's military says 17 people, mostly foreign militants, and a soldier have been killed in a clash near the Afghan border.
Soldiers had surrounded houses in Miran Shah, North Waziristan, overnight and engaged in a six-hour gun battle.
The military said the insurgents tried to break out using women as human shields, some of whom were killed.
Pakistan has about 70,000 troops in the tribal regions tackling militants with suspected al-Qaeda and Taleban links.
The military said troops had surrounded the suspected militants at about 2200 (1700GMT) on Saturday in Miran Shah, 300km (180 miles) south-west of Islamabad.
Security forces had received a tip off about the presence of foreign militants, a military statement said.
It said the army tried to persuade the foreign militants to surrender but they tried to break the security cordon in two vehicles, firing upon security personnel and throwing grenades.
The military destroyed one vehicle and stopped the other. An unspecified number of women and what the statement described as "young members" were killed.
Four injured militants were arrested along with 16 local tribesmen the military says were helping militants.
Arms and ammunition including detonators and explosives, were recovered, the statement said.
Security officials recovered four Kazakh passports and said that all of the militants were central Asians.
Pakistan's army believes hundreds of al-Qaeda fighters, including Arabs, Chechens, central Asians and Afghans are still hiding in the tribal region.
Bodies of 24 suspected Taleban soldiers were found on Friday
Many are thought to have fled there after the fall of the Taleban regime in Afghanistan in 2001.
Afghanistan has repeatedly said militants use the region to launch raids against US-led coalition and Afghan forces.
Pakistan says it has carried out regular raids against suspected militant bases in the tribal region over the past two years.
On Friday, Pakistani security forces said they had found the bodies of 24 suspected militants in North Waziristan.
They said the bodies were thought to be those of men killed in fighting with US-led forces on the Afghan side.
Also on Friday, Pakistani President Pervez Musharraf ordered a new crackdown on militant Islamic activities in the country as part of an anti-terrorism drive.