The U.S. military said on Thursday it believed the real name of al Qaeda in Iraq's new leader was Abu Ayyub al-Masri.

"We think that Abu Ayyub al-Masri is in fact, probably, Abu Hamza al-Muhajir. They are probably one and the same," Major General William Caldwell, the spokesman for the U.S. military in Iraq, told a news conference.

Al Qaeda named Muhajir the successor to Abu Musab al-Zarqawi, who was killed last week in a U.S. air strike.

Al-Masri, an Egyptian, trained in Afghanistan and formed al Qaeda's first cell in Baghdad.

In a statement posted on a Web site on Tuesday and signed by Muhajir, al Qaeda vowed to avenge the killing of Zarqawi.