British and American newspapers on Friday published photos showing an imprisoned Saddam Hussein clad in his underwear and washing his laundry.
This prompted an angry US military to launch an investigation and the Red Cross to say the photos may violate the Geneva Conventions.
Britain's The Sun and the New York Post said a U.S. military official, whom it did not identify, provided the photos. The photos not only angered the US military, which issued a condemnation rare for its immediacy, but also were expected to further fuel anti-American sentiment in a country edging toward open sectarian conflict.
Senior aides briefed President Bush on Friday morning about the photos' existence.
Bush "strongly supports the aggressive and thorough investigation that is already underway" that seeks to find who took them, White House spokesman Trent Duffy said.
Photos show Saddam clothed and seated on a chair doing some washing, sleeping and walking in what is described as his prison yard.
"The specific issue here is that these images are against (Department of Defence) policy. It's not the content of the photo that is the issue at hand, but it is the existence or release of the photos," U.S. military spokesman Staff Sgt. Don Dees said.
He added that the military would question the troops holding Saddam as part of its investigation.
"We take seriously our responsibility to ensure the safety and security of all detainees," a military statement said.
The military said the source of the photos was not immediately known, but they were believed to have been taken more than a year ago.
Saddam was captured in December 2003 while hiding in a concealed hole in the ground near his hometown of Tikrit, 80 miles north of Baghdad. He is charged with war crimes, but no date has been set for his trial.
It is not the first time there has been an outcry over images of Saddam.
Pictures and video images of Saddam being examined by a medic after his arrest were widely criticised, even by the Vatican. A top Vatican cardinal said at the time that American forces treated the captured Iraqi leader "like a cow."
(Associated Press reporters Bassem Mroue in Baghdad and Jill Lawless in London contributed to this report.)