The death of secret detainee Manadel al-Jamadi was ruled a homicide in a Defense Department autopsy, Time reported, adding that documents it recently obtained included photographs of his battered body, which had been kept on ice to keep it from decomposing, apparently to conceal the circumstances of his death.

The details about his death emerge as US officials continue to debate congressional legislation to ban torture of foreign detainees by US troops overseas, and efforts by the George W. Bush administration to obtain an exemption for the CIA from any future torture ban.

Jamadi was abducted by US Navy Seals on November 4, 2003, on suspicion of harbouring explosives and involvement in the bombing of a Red Cross centre in Baghdad that killed 12 people, and was placed in Abu Ghraib as an unregistered detainee.

After some 90 minutes of interrogation by CIA officials, he died of 'blunt force injuries' and 'asphyxiation', according to the autopsy documents obtained by Time.

A forensic scientist who later reviewed the autopsy report told Time that the most likely cause of Jamadi's death was suffocation, which would have occurred when an empty sandbag was placed over his head while his arms were secured up and behind his back, in a crucifixion-like pose.

Blood was mopped up with a chlorine solution before the interrogation scene could be examined by an investigator, Time wrote, adding that after Jamadi's death, a bloodstained hood that had covered his head had disappeared.

Photos of grinning US soldiers crouching over Jamadi's corpse were among the disturbing images that emerged from the Abu Ghraib prison scandal in 2004, prompting international outrage and internal US military investigations.

Last week, the New Yorker magazine reported that the US government's policies on interrogating terrorist suspects may preclude the prosecution of CIA agents who commit abuses or even kill detainees, and said the CIA had been implicated in the death of at least four detainees.

Mark Swanner, the CIA agent who interrogated Jamadi, has not been charged with a crime and continues to work for the agency. He told investigators that he did not harm Jamadi, Time wrote.