The SBS network's "Dateline" program broadcast the pictures and videos Wednesday, including images of prisoners at Baghdad's Abu Ghraib prison apparently forced to engage in sex acts and several images of corpses.
However, the images were taken in 2003, the same time that previously released photographs of prisoner abuse were taken and charges were laid, CNN said.
U.S. State Department legal adviser John Bellinger said there was no news value in the images and the government had not released them earlier "because we felt it was an invasion of the privacy of the people in the pictures."
Pentagon spokesman Bryan Whitman also was critical of the network's decision, saying hundreds of U.S. soldiers had been prosecuted over past abuses, including 25 at Abu Ghraib.
Seven low-ranking guards and two military intelligence soldiers have been disciplined for offenses documented in the original pictures.