( CNN ) -- Al Qaeda ended days of speculation Sunday by confirming that one of its chemical weapons experts was killed last week along with three other `` heroes , '' according to a statement posted on a radical Islamist Web site . Midhat Mursi al-Sayid Umar was among four `` heroes '' killed last week , an al Qaeda statement says . The statement , dated July 30 , provided no details on how or when the al Qaeda operatives were killed . It was signed by al Qaeda 's top leader in Afghanistan , Mustafa Abu al-Yazid . A senior Pakistani official said last week it was a `` near certainty '' that weapons expert Midhat Mursi al-Sayid Umar died in a U.S. airstrike Monday in Pakistan 's tribal region . Pakistani Prime Minister Yousuf Raza Gilani said that if reports of the strike were true , the U.S. violated Pakistani sovereignty . Umar , who is also known as Sheikh Abu Khabab al-Masri , was on the U.S. State Department 's list of 37 wanted terrorists , and the U.S. had offered $ 5 million for information leading to his death or arrest . `` Although Abu Khabab is gone , he left behind him a generation who will seek revenge and punishment with God 's help , '' the al Qaeda statement said . `` And while the 'expert ' is gone , he left behind experts who were taught and trained under his hands throughout the years . '' Umar was killed along with Abu Mohammed Ibrahim Bin Abi al-Faraj al-Masri , Abd al-Wahab al-Masri , and Abu Islam al-Masri , the statement said . Umar , a 55-year-old Egyptian , ran a chemical-and-explosives training camp for terrorists in Derunta , Afghanistan , before the fall of the Taliban , U.S. officials said . `` Since 1999 , he has distributed training manuals that contain instructions for making chemical and biological weapons , '' according to the U.S . Rewards for Justice program . `` Some of these training manuals were recovered by U.S. forces in Afghanistan . '' Rewards for Justice said Umar was believed to be in Pakistan , continuing to train al Qaeda terrorists and other extremists . He was reportedly near the site of a U.S. airstrike more than two years ago in the Pakistani mountain village of Damadola . The strike targeted a dinner gathering believed to include terrorists . Initial reports that Umar died in the January 2006 strike later proved erroneous .
Statement provides few details , is signed by al Qaeda leader in Afghanistan . Statement : Weapons expert `` left behind him a generation who will seek revenge '' Pakistani PM said if U.S. conducted airstrike , it violated Pakistani sovereignty . Reports that al Qaeda weapons expert was killed in 2006 proved erroneous .