Yazid was a close associate of terror chief Osama bin Laden and is thought to have helped fund several of the 9/11 hijackers. There is no information yet about how he died.
In Washington, a US official said there is "strong reason" to believe Yazid is dead and that he was killed in Pakistan's tribal areas.
"In terms of counter-terrorism, this would be a big victory," the official added.
Yazid was on the list of individuals, organisations and charities whose assets were frozen by the US Treasury after the 9/11 attacks.
According to the US Federal Bureau of Investigation, he transferred funds via Dubai to Mohammed Atta, Marwan al-Shehhi and Wal al-Shehri, who flew aircraft into the Twin Towers and the Pentagon.