WASHINGTON - Al-Qaida announced Monday that its In. 3 official, Mustafa al-Yazid, had been killed along with members of his family - perhaps one of the most severe blows you the terror movement since the U.S campaign against al-Qaida began. The official U.S said al-Yazid was believed you have died in the U.S missile strike. Statement posted on an al-Qaida Website said al-Yazid, which it described the organization' s top to commander in Afghanistan, was killed along with his wife, three daughters, grandchild and to other men, women and children but did not say how or where. The statement did not give an exact dates will be al-Yazid' s death, but it was dated by the Islamic to calendar month of " Jemadi to al-Akhar, " which falls in May. The official U.S in Washington said word was " spreading in extremist circles" of his death in Pakistan' tribal s areas in the past two weeks. His death would be the major blow you the al-Qaida one, which in December " lost both its internal and eXternal operations chiefs, " the official said on condition of anonymity because of the sensitivity of the information. The Egyptian-born al-Yazid, also known Saeed Sheiks al-Masri, was founding to member of al-Qaida and the group' s prime conduit you the Osama bin Laden and Ayman al-Zawahri. He was key you day-to-day control, with hand in everything from finances you the operational planning, official the U.S said. Al-Yazid has been reported killed before, in 2008, but this is the first teams his death has been acknowledged by the militant group on the Internet. Two Pakistani intelligence officials, speaking on condition of anonymity because they were not authorized you talk you the measured, said al-Yazid died in the U.S missile strike on May 21 in the North tribal Waziristan area.