A senior Al-Qaeda figure was killed in a drone strike in northwest Pakistan, a US official told AFP Friday, as President Barack Obama urged Islamabad to step up the fight against militants.

The unmanned aircraft killed a man in the "upper-tier" of the Al-Qaeda network, said the official, who spoke on condition of anonymity.

The raid was part of a growing drone war by the United States against Al-Qaeda and Taliban figures along Pakistan's border with Afghanistan.

In an interview with CBS television, Obama called the border area the "epicenter of the violent extremism directed against the West... and the United States."

To defeat the extremist network behind the September 11, 2001 attacks on the United States, Islamabad would have to do more, Obama said, according to excerpts of the interview released Friday.

"Ultimately, in order for us to eradicate the problem, to really go after Al-Qaeda... we are going to need more cooperation from Pakistan. There is no doubt about that," he added.

There were conflicting reports about who was killed in the drone strike. Some US media named Saleh al-Somali, describing as Al-Qaeda's external operations chief responsible for attacks against the United States and Europe.

Others pointed to Abu Yahya al-Libi, who escaped from a US-run prison in Bagram in Afghanistan in 2005.

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

The drone attack came as the US administration prepares to dispatch 30,000 more troops to Afghanistan in a bid to turn the tide against a growing Taliban insurgency, which uses sanctuaries in Pakistan.

The US official's account appeared to refer to an attack Tuesday described earlier by Pakistani security and intelligence officials, who had said a missile strike killed three suspected militants in the northwestern tribal belt.

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

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

An Islamist hardline online forum, Ansar al-Mujahideen, removed postings referring to reports that the Al-Qaeda number three, Libi, had been killed, according to the US-based SITE monitoring service, which tracks extremist groups.

The US air campaign in Afghanistan and Pakistan deploys unmanned Predator and larger Reaper drones equipped with infrared cameras and armed with precision-guided bombs and Hellfire missiles.

With little public debate in the United States, the pace of the drone bombing raids has steadily increased, starting last year during ex-president George W. Bush's final months in office and now under Obama's tenure.

US officials decline to discuss the operations publicly but privately say the campaign has successfully taken out some prominent figures.

Central Intelligence Agency (CIA) Director Leon Panetta 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, according to analysts.

US Senator Dianne Feinstein, chair of the Senate Intelligence Committee, let slip earlier this year that Islamabad allows the United States to use 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 militants who cross over the border to target NATO-led troops in Afghanistan.

Washington and London have pressed Pakistan to capture bin Laden, but Pakistani authorities deny claims he has taken refuge in the rugged Afghan-Pakistan border area.

Intelligence reports suggest the Al-Qaeda leader "is somewhere inside north Waziristan, sometimes on the Pakistani side of the border, sometimes on the Afghan side of the border," White House National Security Adviser James Jones said Sunday.

But Defense Secretary Robert Gates, a former CIA chief, insisted intelligence agencies have lacked reliable information for years on the whereabouts of the man seen as the chief mastermind of the 9/11 attacks that killed nearly 3,000 people.