Pakistani troops have killed at least 35 militants near the north-west border with Afghanistan, the army says.
Military spokesman Maj-Gen Waheed Arshad said fierce clashes in the North Waziristan tribal area began late on Sunday night and were still continuing.
Two soldiers had been killed and seven others wounded, the military said.
Dozens of security force personnel have been killed by the militants since the army stormed a controversial mosque in Islamabad earlier in July.
The military said the fighting started when two army check posts in the town of Mir Ali in the Miranshah area were attacked by militants.
Afterwards the army "took action to apprehend" the militants using helicopter gunships and artillery, a spokesman told the BBC.
Last Wednesday officials said that at least 17 Pakistani soldiers had been killed in the area in an ambush by militants. Twelve militants were also reported to have died in the clash.
At that time President Musharraf ruled out declaring an emergency in the country.
There have been a spate of attacks - most in the north-west - since soldiers stormed the radical Red Mosque in the capital.
The mosque assault prompted militants along the border to scrap controversial peace accords with the government.
The government has said it wants to revive the accord in order to root out foreign militants in the area and curb cross border incursions into and from Afghanistan.
Correspondents say that the Waziristan region has long been seen as a safe haven for al-Qaeda and Taleban militants.
A US intelligence report released last week said that al-Qaeda had re-grouped and gained strength in the north-western border area.
But the Pakistani foreign ministry denied that was the case, arguing that the report contained "unsubstantiated assertions" which were not backed up by concrete and actionable intelligence.
Around 180 people, mostly police and soldiers, have been killed since the attack on the Red Mosque began on 3 July.