Pakistani soldiers launched an operation in Bajaur in August
Pakistani troops have killed four militants in the Bajaur tribal district near the Afghan border, the army says.
The clash started when militants attacked a security post in the Nawagai area, a military official told the BBC.
This is the first clash in the area since 23 February when a senior Taleban leader announced a unilateral truce.
The military says the Bajaur operation, which began last August, is proof of its commitment to tackle the Taleban in the restive north-west.
The Bajaur truce came a week after a deal was signed between Pakistani officials and Taleban representatives to end an insurgency in the Swat region in return for the imposition of Sharia law.
Taleban 'to disarm'
Administration officials in Khar, the central town of Bajaur, say militants attackedsecurity forces on Sunday night.
Since the attack, the artillery guns stationed in the Khar garrison have been pounding militants' positions in the Nawagai area.
Witnesses say that security forces have also launched a search operation in the area to flush out militants.
Later on Monday, tribesmen in Bajaur signed a peace deal with the local administration.
"Under the deal, all militant organisations in Bajaur will be disbanded," a government official told the BBC Urdu service from Khar.
"The Taleban will give up their arms and present themselves to the government."
There was no immediate response from the militants to the deal or to the latest clashes.
The BBC's Syed Shoaib Hasan in Islamabad says the agreement is believed to have been made after protracted negotiations between the tribesmen and the Taleban leaders.
Our correspondent says it is highly unlikely that the tribesmen would agree to such a deal with the government without the consent of the militant leadership.
Meanwhile, there is no confirmation of the identity of the militants killed in the clash with security forces in the Nawagai area of Bajaur.
Nawagai is close to the Mohmand tribal region.
Local Taleban militants in that area have recently been involved in clashes with Pakistan's security forces, although there is no operation currently being conducted in Mohmand.
Officials say that since the Bajaur ceasefire in late February, militants have intensified their activities in Mohmand.
On Sunday, militants in Mohmand's southern Ekkaghund area killed 14 members of a tribal police force called "khasadars".
The khasadars, along with a local administration official, had gone missing during a clash with militants on Saturday night.
Villagers found their bodies strewn around a hill and a nearby ravine on Sunday.
An administration official in Mohmand told the BBC Urdu service's Dilawar Khan that the clash started when the khasadars foiled an attempt by the militants to kidnap a local pro-government elder.
A spokesman for the Mohmand Taleban, Ikramullah, told the BBC: "We don't want to kill khasadars, but what can we do when they offer resistance to our people?"
He also admitted that the Taleban were holding a mid-level administration official, Arshad Ali.
Officials and witnesses say the administration is in contact with some local elders who are negotiating Mr Ali's release.