Izzat Ibrahim al-Douri, aide to Saddam Hussein, died on Friday, al-Arabiya TV channel quoted a statement by the Baath party as saying.
Al-Douri, vice chairman of the Revolutionary Command Council under Saddam's regime, ranks No. 6 among the 55 most wanted by the United States with a 10-million-dollar bounty on his head.
He died early Friday, the statement said, without giving more details. He was reportedly suffering from leukemia.
Al-Douri, a Sunni, was one of Saddam's confidants who helped the now dissolved Baath party sweep to power in the 1960s.
He was also alleged to be responsible for ethnic repressing against Kurds and Shiites.
In September 2004, reports emerged that he had been captured, which were later declared to be erroneous.