Pakistan's military said its forces have killed 55 to 60 Taliban militants in the last 24 hours in heavy fighting in Taliban-held areas of the northwest.
While Pakistani forces captured the main town in Buner hours after the offensive began on Tuesday, troops continue to battle Taliban fighters for control of high strategic positions.
Army spokesman Major General Athar Abbas said militants are using a variety of powerful weapons, including anti-aircraft machine guns bolted to trucks, mortars and improvised bombs to try to block one of the main routes into Buner.
"Fierce fighting took place at the northern area of Ambela Pass. The forces came across a lot of IEDs, prepared suicide vehicles, suicide motorcycles, individual suicide bombers and a group of 70 to 80 militants occupying the heights of Ambela Pass," he said.
Groups of nearly 150 militants have overrun security checkpoints and police stations during the fighting. The military has reported just a few casualties among police and paramilitary troops, but dozens of security forces have been reported kidnapped by militants. The military said most of them have been released, unharmed.
More than 100 militants have been reported killed since the operation began Sunday.
In Dir, which the army said it took control of days ago, fighting continues. General Abbas said troops killed as many as 10 suspected militants Friday who were trying to enter Dir from Bajaur, the neighboring tribal agency.
Much of the fighting is now focused on Buner, where the military has relied heavily on airstrikes. The army has provided little information on civilian casualties. Previous counterinsurgency campaigns in neighboring Swat failed in part when local support for the operations eroded because of civilian deaths.
Sardar Hussain Babak, a provincial lawmaker from Buner, said that although civilian casualty figures remain uncertain, locals continue to support the campaign.
"Since one month they were living in a very uncertain condition and they were very frustrated because of these militants. But as a whole all the locals of the district are satisfied," he said.
The majority of militants in Buner are believed to be from neighboring Swat although some foreign militants have been reported among the fighters. The military said the militants are receiving outside support from Pakistan's Taliban-controlled tribal areas as well as militant groups in southern Punjab province.
While security forces have stopped their offensive at Swat's border, Army spokesman Abbas said militants have tightened their grip on the valley. He said this week fighters have set up at least eight checkpoints, kidnapped 14 police, government officials and aid workers and executed three civilians.
Abbas said all of those actions are in violation of the Swat peace agreement, which was aimed at avoiding confrontation by establishing Islamic law in the region.
Provincial officials and the peace agreement mediator met Friday. They said despite the violence, they still hope to implement the deal by establishing Islamic courts throughout the northwest Malakand division.