The man, identified as Hamid Juma al-Saidi, was named as one of the organizers of the February bombing of a Shi'ite shrine in the city of Samarra.
That bombing inflamed tensions between Shi'a and Sunnis, leading to an upsurge in sectarian violence that continues to this day.
Al-Rubay'i said al-Saidi provided information that has led to the arrest or death of 11 other top figures of Al-Qaeda in Iraq and nine lower-level members.
Also today, the U.S. military said two of its soldiers were killed in eastern Baghdad early on September 3 when their vehicle hit a roadside bomb.
More than 2,000 U.S. troops have been killed by hostile action in Iraq since the U.S.-led invasion began in March 2003.
(compiled from agency reports)