The Pentagon has become embroiled in a row after the US Army released a photo of a general to the media which was found to have been digitally altered.
General Ann Dunwoody was shown in front of the US flag but it later emerged that this background had been added.
The Associated Press (AP) news agency subsequently suspended the use of US Department of Defense photos.
A Department of Defense spokeswoman insisted that the photo had not violated army policy.
Gen Dunwoody, the highest ranking US female military officer, was recently promoted to become a four-star general.
In an original photo of her, she appears to be sitting at a desk with a bookshelf behind her.
The altered photo, distributed by the army and initially sent by AP to its clients around the world, shows Gen Dunwoody against a background of the stars and stripes.
When the digital alteration was discovered, AP immediately withdrew the photo and began an investigation.
AP says that adjusting photos and other imagery, even for aesthetic reasons, damages the credibility of the information distributed by the military to news organisations and the public.
"For us, there's a zero-tolerance policy of adding or subtracting actual content from an image," said Santiago Lyon, AP's director of photography.
Mr Lyon said AP was developing procedures to protect against further occurrences and, once those steps were in place, it would consider lifting its ban on the use of US Department of Defense photos. He said AP was also discussing the problem with the military.
Colonel Cathy Abbott, chief of the US Army's media relations division, said the Dunwoody photo did not violate army policy that prohibited the editing of an image to misrepresent the facts or change the circumstances of an event.
She added that she did not know who had changed the photo or which office had released it.
"We're not misrepresenting her," Col Abbott said. "The image is still clearly Gen Dunwoody."
In September, AP banned use of a photo of Darris Dawson, a soldier who was killed in Iraq, in which his face and shoulders appeared to have been digitally altered.
Col Abbott said his unit did not have an official photo of him and wanted one that could be used for a memorial service.
"That photo was released to the public strictly by accident," she said. "We apologised for that."
The Dunwoody incident is the latest example of pictures being apparently doctored before being presented to the world's media.
In July, Iran was accused of altering an image of a missile test.
Correspondents say it was an apparent attempt to cover up the fact that one of the missiles had misfired.