WASHINGTON - A senior Al-Qaeda leader has been killed in a drone strike in northwest Pakistan, a US official told AFP on Friday.

The person killed was an "upper-tier" figure in the Al-Qaeda network, said the official, who spoke on condition of anonymity.

The raid was part of a growing bombing campaign by the United States against Al-Qaeda and Taliban figures in tribal areas of Pakistan and came amid CBS reports that the man killed was the Al-Qaeda number three, Abu Yahya al-Libi.

The operation did not target Al-Qaeda's leader, Osama bin Laden, or his Egyptian deputy, Ayman al-Zawahiri, officials said.

The drone attack comes as the US administration prepares to send 30,000 reinforcements in neighboring Afghanistan to try to turn the tide against a growing Taliban insurgency, which uses sanctuaries in Pakistan.

The US official's account came after Pakistani security and intelligence officials reported a missile strike from a US drone killed three suspected militants in the northwest tribal belt early Tuesday.

The attack targeted a car in Aspalga village, about 12 kilometers (seven miles) southeast of Miranshah, the main town of the restive North Waziristan tribal district bordering Afghanistan, officials said.

North Waziristan neighbors South Waziristan, where Pakistan has been focusing its most ambitious offensive yet against homegrown Taliban militants, deploying about 30,000 troops into the region from October 17.

The US air campaign employs unmanned Predator and larger Reaper drones armed with precision-guided bombs and Hellfire missiles to target Al-Qaeda leaders.

Officials privately say the campaign has successfully taken out some prominent figures and the director of the CIA has defended the attacks as "the only game in town" when it comes to targeting Al-Qaeda and its allies.

Islamabad publicly criticizes the targeted assassinations but quietly cooperates with the operations, analysts say.

US Senator Dianne Feinstein let slip at a congressional hearing earlier this year that Islamabad allows the use of an air base on Pakistani soil for the drones.

Islamabad is under increasing Western pressure to not only target Taliban groups attacking Pakistan, but also Al-Qaeda-linked fighters and the militants who cross over the border and target foreign troops in Afghanistan.

Washington and London have also pressed Pakistan to capture bin Laden -- believed to be in the rugged Afghan-Pakistan border area -- but the authorities deny he is on their soil.