(CNN) -- The Marine Corps is working to determine the authenticity of photos published by TMZ.com that purport to show Marines burning the bodies of what appear to be Iraqi insurgents.
The celebrity and gossip website said it has 41 photographs believed shot in Falluja in 2004. It published eight on Wednesday, saying the rest of the images were too graphic.
"The actions depicted in these photos are not what we expect from our service members, nor do they represent the honorable and professional service of the more than 2.5 million Americans who have served in Iraq and Afghanistan," the Defense Department said.
"The Marine Corps is currently investigating the veracity of these photos, circumstances involved, and if possible, the identities of the service members involved. The findings from this investigation will determine whether we are able to move forward with any investigation into possible wrongdoing."
Among the published photographs, a person in a Marine uniform appears to be pouring gasoline or some other flammable liquid on the bodies of insurgents. The remains are shown ablaze, and then charred.
Islamic custom strictly forbids cremation.
In another photograph, a Marine poses for the camera next to a human skull.
"There are well over a dozen bodies in the pics and some are covered with flies and one is being eaten by a dog," TMZ.com reported.
It said it turned the photographs over to the Pentagon last week and that U.S. Central Command had reviewed them to see whether they had previously been brought to its attention. They had not.
During the Iraq war, Falluja was the site of some of the bloodiest fighting between U.S. forces and insurgents. The battles were among the worst Marines had seen since Vietnam, said former Marine Capt. Jonathan Rue.
"This looks really bad, but we don't know exactly what was happening, and we don't know what the circumstances were. Nor do we know exactly who was in those photos," he said.
If the images prove authentic, it wouldn't be the first time Marines have come under fire for the treatment of enemy bodies.
In July 2011, Marines urinated on dead Taliban fighters and posed for photographs with the corpses in Helmand Province, Afghanistan.
The incident did not come to light publicly until January of the following year, when a 39-second video showing the desecration was posted on the Internet. The video inflamed tensions over the U.S. presence in Afghanistan.
"People in battlefield situations do very strange and reprehensible things, and maybe that's simply part of life, and that's why you need to have a military justice system that can punish people and hopefully discourage this kind of conduct in the future," said Eugene Fidell, with Yale Law School, in response to the recently-published photographs.
"That isn't going to be an answer however to people in Iraq, who are likely to be very infuriated by this."