Al-Qaeda's second-in-command Abu Yahya al-Libi was killed in Monday's drone attack on Pakistan, US officials have confirmed.
The killing of Abu Yahya al-Libi is thought to be the biggest setback to the terror network since the death of Osama bin Laden. "There is no-one who even comes close in terms of replacing the expertise Al-Qaeda has just lost," one US official told the BBC.
The missiles dropped on a militant compound in the tribal region of North Waziristan, near Pakistan's border with Afghanistan on Monday was aimed at Libi, according to US intelligence.
However the death of the militant leader was only confirmed by the White House on Wednesday and is yet to be confirmed by Pakistan.
The death of Abu Yahya al-Libi will be a 'major blow' to Al-Qaeda one US official said on Monday
Libi was said to be a kind of "general manager" for Al-Qaeda, according to Newsweek Pakistan, organising the day-to day running of the militant organisation.
He was the media-savvy, charismatic leader that also had religious credentials, backing Egyptian-born Al-Qaeda, Ayman al-Zawahri who took over leadership of the institution when Osama Bin Laden was killed.
He was helping preside over the transformation of a secretive group based in Pakistan and Afghanistan into a global movement aimed at winning converts - and potential attackers - from Somalia to the Philippines. Abu Yahya al-Libi is said to have attracted younger generations to Al Qaeda, and had become the most visible face of the organisation in recent years, reports the BBC.
In 2009, Libi, whose real name is Mohamed Hassan Qaid, was wrongly reported dead after a case of mistaken identity.
Reports from Pakistani sources suggested that Libi was either severely injured or killed on Tuesday. Conversations intercepted by Pakistan intelligence revealed militants discussing "the death of a 'sheikh'" according to Reuters.
Monday's drone attack was the deadliest this year, with Pakistan's foreign ministry labelling the strike 'illegal' reports Reuters.
Over the weekend, three attacks were launched along the Afghan border, with Pakistani sources claiming that 30 people were killed.
Drones are a source of friction in the increasingly taught relationship between Pakistan and the US, with Pakistan claiming the weapons kill civilians and drum up anti-American sentiment.
However the success of Monday's airstrike is likely to strengthen American arguments that drones are a vital weapon in the war against terrorism.
According to the New York Times, President Obama personally approves each strike.
Relations have been furthered strained between the countries after Pakistan sentenced a doctor who played a key role in helping the CIA confirm the presence of Osama Bin Laden.
Dr Shakil Afridi was found guilty of treason and sentenced to a 33-year-jail sentence for his part in running a DNA collection scheme.
US Defense secretary Leon Panetta told CBS television that Dr Afridi "was not in any way treasonous towards Pakistan... for them to take this kind of action against somebody who was helping to go after terrorism, I just think is a real mistake on their part".