Australia was an ''integral'' element of the potentially illegal detention of prisoners of war at a secret Iraqi desert prison in 2003, according to a British newspaper, citing a US military document.
The revelation has led to an Australian human rights organisation investigating such secret prisons to claim that the Australian military might have been complicit in war crimes by handing detainees over to the so-called ''black site'' known as H1.
The revelations - which the Defence Department last night denied, saying it was only ''providing security'' when the detainees were handed over - would be the first time the Australian military has been implicated in the black sites.
Black sites were secret prisons, which became infamous after the 2003 Abu Ghraib scandal, and were used by a US military unit codenamed Task Force 6-26 to interrogate enemy fighters.
According to a 2006 New York Times investigation, detainees at such prisons were beaten, waterboarded, spat on and tortured.
Up to this point Australia has never been accused of involvement in such incidents.
However, yesterday The Guardian published an article by Ian Cobain which stated that the Australian SAS squadron of 150 men working in Iraq, codenamed Task Force 64 by the US, was an ''integral'' part of H1's operation.
The claim is based on a ''US field inquiry report'', which according to The Guardian reveals that a British special forces unit and Task Force 64 ''were an integral part of operations at H1. Both units were under US tactical control''.
As of last night, the Herald has been unable to see the actual US report.
According to sources who spoke to The Guardian, interrogations at the site were carried out by the CIA and MI6.
The revelations were initially sparked by the death of a 43-year-old Iranian named Tanik Mahmud, who was captured by Australian SAS soldiers in April 2003 along with 63 other Iraqis and Syrians.
The men were handed over to British soldiers and loaded onto Chinook helicopters during the night of April 11.
Last year the Herald revealed that Mahmud, who died along with another detainee aboard one of the Chinooks that night, may have been beaten to death by two British soldiers.
What was not known was where they were being taken to. But yesterday The Guardian reported that the 64 men were in fact taken to the secret prison in the middle of Iraq's western desert.
H1 was an Iraqi air force base captured by coalition forces early in the war to launch operations deeper into Iraq.
Asked whether ''Australian troops ever sent prisoners or detained persons to H1'', Defence issued a one word response: ''No.''
However, a declassified Australian military document from 2003 which deals with Mahmud's death suggests otherwise.
The document states that the 64 detainees ''were handed over to the UK extraction FE and UK aircrew for transit to an EPW handling facility at H1.'' FE is a military term for a group of soldiers. EPW means enemy prisoners of war.
When presented with that document, Defence responded: ''Australia was not the detaining power during operations in Iraq in 2003 [and] therefore was not responsible for the transfer or detention of any detainee.''
Last night the human rights organisation that has been investigating illegal detention in Iraq and Afghanistan, the Public Interest Advocacy Centre in Sydney, said the Australian government now needed to clarify exactly what it knew about H1 and other secret prisons.
The chief executive, Edward Santow, said international humanitarian law had clear rules regarding capturing and detaining prisoners of war.
''If the 'H1' facility was a secret prison, hidden from the Red Cross and with no external oversight, this would breach the Geneva Conventions and international law,'' he said.
''These new revelations cast further doubt on the Australian military's compliance with international law.''
The prison was so secret that its existence was not disclosed to Britain's most senior military lawyer in Iraq in 2003, Lieutenant-Colonel Nicholas Mercer.
He told The Guardian he was ''extremely surprised'' to learn of its existence.
''It appears from the information disclosed that some prisoner operations were being conducted, deliberately or otherwise, outside of the chain of command.''
The Herald has also confirmed that some of the most senior Australian military officers involved in the war in Iraq at the time were unaware of the secret facility at H1.
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