Pakistan artillery attacked Taliban targets in the northwest on Thursday as President Asif Ali Zardari asked Washington for "ownership" of US drones killing militants on its territory.
More than 670,000 civilians registered as displaced with the United Nations after fleeing the offensive in the northwest, where the Taliban have terrorised the population in a campaign to enforce sharia law and expand their control.
Artillery batteries shelled suspected hideouts in Swat and the neighbouring district of Lower Dir, but there were no immediate reports of new casualties on the 18th consecutive day of operations in the northwest.
"Militant hideouts were targeted in Dir and Swat and many of their hideouts were destroyed in mountains," one security official told AFP on condition of anonymity because he was no authorised to talk to the media.
The International Committee of the Red Cross said it entered Buner, one of the hardest hit areas in the conflict zone, for the first time since fighting broke out, in order to deliver medicines and surgical materials.
"You can see the scars of recent fighting," said Bart Janssens, the ICRC's health coordinator in Pakistan.
"There is no more electricity or clean drinking water. Most shops are closed. Goods on the market are scarce. The streets feel empty. The district is rapidly being emptied of its inhabitants," he said.
The relief agency said it hoped to bring more aid to the civilians caught in the battle between the military and the Taliban "in the coming days."
The military launched an offensive on April 26 after armed Taliban advanced to within 100 kilometres (60 miles) of Islamabad from Swat, once a picturesque ski resort frequented by Westerners and now a hub of Islamist violence.
The military says up to 15,000 troops are taking on about 4,000 well-armed fighters in Swat, where Islamabad has ordered a battle to "eliminate" Islamist militants, branded by Washington as the greatest terror threat to the West.
UN Secretary General Ban Ki-moon expressed "deep concern" about the situation in the area, where the UN refugee agency said 670,906 stranded people had registered.
Overall, the military says, more than 750 militants and 33 troops have been killed in its operations in Lower Dir, Buner and Swat, although there is no independent confirmation of the figures and no word on civilian casualties.
Holding talks in London en route back to Pakistan after a summit with US President Barack Obama, Zardari said he asked Washington for "ownership" of US drones carrying out attacks on its territory.
"Democracy doesn't believe in half measures. We've asked for the ownership of the drones," he said, when asked about reports that the United States has agreed to pass control of drone aircraft to the nuclear-armed Muslim country.
Zardari said Islamabad was "negotiating terms" with the United States over the drones, a fount of tension between Washington and Islamabad.
Pakistan is opposed to the drone attacks, more than 40 of which have killed over 390 people since August 2008, saying they violate its territorial sovereignty and deepen public resentment.
Zardari branded the fight against the Taliban a long-term struggle but dismissed suggestions that Pakistan's nuclear arsenal was vulnerable.
Prime Minister Gordon Brown announced Britain would provide 12 million pounds ($18.2 million) in immediate humanitarian aid to help ease the plight of civilians caught up in the fighting.