April 9, 2008 -- U.S. government officials tell ABC News they believe a key figure in the planning of the alleged 2006 plot to blow up airliners flying from the UK to the U.S. has recently died.
Top al Qaeda operations planner Abu Obaidah al-Masri was last believed to be hiding along the Afghanistan-Pakistan border.
Al-Masri, an Egyptian (Masri means "Egyptian" in Arabic), was also allegedly responsible for planning the July 2005 London subway bombings which killed 52 people and injured hundreds, officials said.
U.S. counterterrorism officials tell ABC News that al-Masri is believed to have died from hepatitis.
Al-Masri is a long-time figure in the terrorist underground, who fought in Afghanistan against the Soviets and then became involved in al Qaeda.