An American news agency says it has seen official papers suggesting that prisoner abuse in Iraq took place at four sites other than Abu Ghraib.
Evidence of abuse has emerged from a marine camp at Nasiriya and army camps at Baghdad International Airport, Qaim and Samarra, the Associated Press says.
Detainees were allegedly beaten or forced to stand for long periods of time in scorching desert heat.
AP examined court transcripts and investigator interviews.
The abuses allegedly committed at Abu Ghraib, the feared Saddam-era prison now run by coalition forces, outraged the world after a stream of photos apparently taken by guards emerged.
According to the military documents seen by AP, at least two detainees held at other sites died of their injuries.
The allegations concerning military intelligence troops include the following:
- At Camp Whitehorse near Nasiriya, guards were allegedly told to prepare prisoners for interrogation by keeping them in hoods in temperatures of up to 49C degrees (120F) for 50 minutes at a time over periods of 10 hours. One Iraqi detainee choked to death.
At a camp near Qaim, interrogators allegedly stuffed an Iraqi general into a sleeping bag, sat on his chest and covered his mouth. Maj Gen Abed Hamed Mowhoush, who had also been questioned by CIA operatives, eventually died.
At a camp near Samarra, prisoners were reportedly choked and beaten and had their hair pulled.
At Camp Cropper, at Baghdad International Airport, prisoners were allegedly beaten and forced to adopt painful positions for hours at a time.
Two marines are facing charges related to the death at Camp Whitehorse in June 2003 although nobody is charged with actually killing the prisoner.
Military records state the victim, named as Nagem Sadoon Hatab, died when a marine guard grabbed his throat in an attempt to move him, accidentally breaking a bone which cut off his air supply.
The other marine is charged with kicking Mr Hatab in the chest in the hours before his death.
In another development, the New York Times newspaper reports that military interrogators from the Guantanamo detention camp in Cuba played a key role at Abu Ghraib.
The interrogators at Guantanamo, which houses al-Qaeda and Taleban suspects, were sent to Iraq last year by the head of the Cuban prison camp, Gen Geoffrey Miller.
Gen Miller was himself sent to Iraq to recommend improvements in the way prisoners were detained and questioned.