Australia's military conspired with US guards to deny the Red Cross access to prisoners held at Iraq's notorious Abu Ghraib jail, including a high-value detainee, said documents published Tuesday.
Its officials also misled the public on the legality of interrogations, before prisoner abuse was exposed in photographs that shocked the world in May 2004, a year after the US-led invasion, a Sydney-based legal lobby group said.
The declassified documents, obtained under Freedom of Information laws, showed a "disturbing response by Australian officials regarding detainee mistreatment" the Public Interest Advocacy Centre (PIAC) said.
Abu Ghraib, west of Baghdad, became infamous in 2004, when the photographs showed that a US military unit had mistreated Iraqi prisoners there.
The pictures severely damaged international opinion about the US war effort and were uncomfortably reminiscent of the torture meted out at the same jail by henchmen of now executed dictator Saddam Hussein's regime.
"The documents raise big questions about ADF (Australian Defence Force) detention practices and the ADF's knowledge of illegal interrogation techniques at Abu Ghraib," said PIAC chief Edward Santow.
Centred on Australia's military representative to Abu Ghraib in 2003-04, George O'Kane, the documents allege Australian complicity with US forces in blocking International Committee of the Red Cross access to prisoners.
O'Kane, a military lawyer, also expressed doubts about the legality of proposed interrogation techniques including sleep and sensory deprivation, warning they were open to abuse and lacked adequate safeguards.
Despite his assessment, defence officials publicly stated the techniques were "consistent with the Geneva Convention", and then-defence minister Robert Hill did not correct that view though he knew it was wrong, PIAC said.
The Australian government relied on this version of O'Kane's findings "to claim that it did not have any early knowledge of the Abu Ghraib abuses," PIAC said.
O'Kane's report was prepared at the request of the US 205th MI Brigade, who PIAC said wanted "top cover" to question a very valuable detainee after being investigated over the death of a prisoner in Afghanistan.
The brigade went on to be implicated in the graphic abuse and humiliation of inmates at Abu Ghraib.
According to the declassified documents, excerpts of which were published by PIAC Tuesday, O'Kane helped block ICRC access to nine prisoners held in cell block 1A, later the site of abuse photographs for which Abu Ghraib is known.
ICRC visits were "regarded as an inconvenience", said PIAC, and US forces "systematically" sought to keep Red Cross representatives away from detainees on grounds of "imperative military necessity".
"If you break someone down, or persuade them to give up information, you don't need them drawing strength from an ICRC visit," O'Kane said of the US rationale for blocking the Red Cross.
O'Kane also knew, and reported to his superiors, that US forces were hiding a high-value detainee, "Triple X", from the ICRC at Abu Ghraib who had been held in Afghanistan and Iraq in breach of international law.
Despite his report the matter was not raised with the US military, and when Canberra found out, they merely passed it on in a memo to the US ambassador "for action as appropriate", PIAC said.
Now a lieutenant colonel, O'Kane was not alone in reporting the abuse of prisoners -- there were claims from other Australian officers made as early as June 2003 that were "lost or ignored" by the defence department, it added.
"The documents show a failure of leadership within Australia's military hierarchy," said Santow, calling for an inquiry similar to that held in Britain into the Iraq war.
"The US and UK have been more open to scrutiny about their involvement in this conflict," he added.
"Australia needs this inquiry to ensure that the ADF has proper procedures in place that ensure our troops abide by international law."
The Australian department of defence did not respond to an AFP request for comment.