ISLAMABAD/WASHINGTON - A US drone aircraft fired missiles at militants in Pakistan on Thursday, killing eight of them, Pakistani officials said, as American officials vowed to press forward with such attacks after US forces killed Osama bin Laden in his Pakistani hideout.

The third such strike since bin Laden's killing on May 2 indicated an intensification of the attacks compared with the weeks before the al-Qaida chief was shot dead in the US raid on a compound in the Pakistani garrison town of Abbottabad.

The US bin Laden raid has embarrassed and enraged Pakistan's military and worsened already strained US ties.

In Washington, debate over whether Bush administration interrogation practices helped find bin Laden heated up when Senator John McCain said torture of detained militants did not help track down the al-Qaida leader.

Pakistani officials said they were expecting soon a $300 million payment from the United States for costs incurred in fighting militants in a payment that comes even as US lawmakers question aid to Pakistan after bin Laden was found there.

The drone strikes anger many Pakistanis and are another source of friction between the allies. Pakistan officially objects to the attacks, although US officials say they are carried out on an understanding with Pakistan.

"There are absolutely no plans at present to cease or scale back US counterterrorism operations in Pakistan," one US official said on condition of anonymity. "Efforts to thwart terrorism will continue."

A drone fired two missiles at a vehicle in the North Waziristan region on Thursday headed toward the Afghan border, killing eight militants, Pakistani officials said.

The CIA regularly launches attacks with pilotless aircraft at militants in Pakistan's Pashtun tribal lands who cross into Afghanistan to battle Western forces there.

The use of missile-armed Predator drones to attack militants has widened a diplomatic divide with Pakistan and sharpened anti-US anger -- but killed few senior militants.

A senior Pakistani security official, asked if Pakistan would take steps to stop the strikes, said there was "nothing of that sort" under way to derail the drone program.

"You have to realize that all (the) equipment you use is theirs, so you can't afford confrontation with them," the official said on condition of anonymity.