The US Army inspector general’s report says only Brig Gen Janis Karpinski, commander at the jail, has been found guilty and reprimanded over the abuse.
Pictures of Iraqi inmates abused by US soldiers caused an outcry last year. Five US soldiers have been convicted.
The Pentagon has held nine major inquiries into the Abu Ghraib prisoner abuse scandal, with two more to come.
US Defence Secretary Donald Rumsfeld is being sued by two civil liberties group for allegedly authorising torture and then failing to stop it.
