Al-Qaeda's second-in-command Abu Yahya al-Libi may have been killed in a drone attack on Pakistan, according to intelligence from a US official.
The missiles dropped on a militant compound in the tribal region of North Waziristan, near Pakistan's border with Afghanistan was aimed at Libi, the official told the BBC.
It has not yet been confirmed whether Libi was one of the 15 people killed. However his death would be a "major blow to core Al Qaeda," the US official said.
"People are looking very closely to see whether he's still alive," an unnamed US official told the New York Times.
Abu Yahya al-Libi is said to have attracted younger generations to Al Qaeda
In 2009, Libi, whose real name is Mohamed Hassan Qaid, was wrongly reported dead after a case of mistaken identity. However US officials are "optimistic" that the drone attack killed the Libyan cleric, reports Associated Press.
Reports from Pakistani sources suggest that Libi has either been severely injured or killed. It “looks like he has been killed” a senior Pakistani security official in Peshawar told the New York TImes.
Conversations intercepted by Pakistan intelligence have revealed militants discussing "the death of a 'sheikh'" reports Reuters.
Pakistani officials believe they are referring to Libi, whose senior position in the organisation is second only to Ayman al Zawahri, an Egyptian-born cleric who took over the leadership of the organisation following the death of Osama Bin Laden.
Libi however, is 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.
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. 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".