At least four Pakistani soldiers and 35 militants were killed in clashes in Kurram tribal region on Friday, local TV channels reported.
Fifteen militants were also injured in clashes at Mauzai area of Kurram agency bordering Afghanistan, Geo television reported.
The Friday's clash broke out after the militants attacked a checkpost of security forces, reports said.
Both sides used heavy weapons including rockets and mortars in the clashes.
Pakistani forces have been conducting major operation against the Taliban militants in Kurram and the nearby Orakzai agency over the past few weeks.
The security forces are also using gunships to target hideouts of the militants in remote and mountainous areas.
Sources said clashes took place when the security forces make advance to clear areas of Taliban militants and to open roads that had been under control of the militants in some remote areas.
On Thursday, five soldiers and 18 militants were killed in an attack on a security forces' convoy and retaliatory shelling by the troops on militants' hideouts in Kurram Agency while nine insurgents were killed in Orakzai Agency clashes, according to local media reports.
During their control in several parts of Kurram and Orakzai tribal areas, Taliban militants had carried out many attacks on the pro-government tribesmen and Shiite Muslims.
Pakistani forces have now cleared most of the areas of Taliban and are also making advance in areas where Taliban are still showing some resistance.