US officials say they believe he was killed recently in the tribal areas of Pakistan in an American drone attack.

Mr Yazid, also known as Sheikh Said al-Masri, died along with his wife and three children, Islamist websites said, quoting a statement from al-Qaeda.

White House spokesman Robert Gibbs said it was "a severe blow" to al-Qaeda.

Mr Gibbs said Mr Yazid was one of the biggest targets to have been killed or captured in five years.

American officials often refer to the Egyptian-born militant as the main conduit to al-Qaeda leader Osama Bin Laden.

As al-Qaeda's operational commander in Afghanistan, Mr Yazid is believed to have had a hand in everything from finances to operational planning.