Hundreds of residents fled their homes on Saturday in Pakistan's northwest tribal region, as security forces continued to target militants.
Pakistani officials say helicopter gunships fired on militants who were trying to damage a road tunnel near the town of Dara Adam Khel (near the city of Peshawar) in the Northwest Frontier Province.
Today's fighting follows clashes that killed up to 30 militants and two soldiers in the town Friday, as Pakistani forces searched for trucks of ammunition and military supplies seized by suspected militants.
Military operations also continue further south in the tribal region of South Waziristan, a stronghold of militant leader Baitullah Mehsud. Mehsud is accused of plotting the assassination of former prime minister Benazir Bhutto.
Meanwhile, Pakistani officials say they have tightened security around all of the country's nuclear facilities following a surge of militant attacks within its borders.
The head of the agency that handles Pakistan's nuclear arsenal, Khalid Kidwai, told foreign reporters on Saturday that, in his words, "the state of alertness has gone up."
However, he said there is no conceivable scenario in which Pakistan will fall to al-Qaida or Taliban type extremists.
Pakistan is estimated to have about 50 nuclear weapons.
Militant groups have launched a rising number of attacks on Pakistani security forces and intelligence personnel in recent months.
US defense leaders have offered to send combat troops to Pakistan to help counter the insurgency, but Pakstani President Pervez Musharraf has rejected the proposal.