Mamduh Habib said he was tortured while in US custody in Pakistan and during interrogation in Egypt, according to his lawyers on Thursday.
A Sydney father of four, Habib was detained in Egypt for six months shortly after his capture in Pakistan in the weeks after the US invasion of Afghanistan.
The former taxi driver has been accused of aiding al-Qaida but has not been charged and few details of the allegations against him have been released.
Supporters want Habib and fellow Australian detainee David Hicks brought back to Australia for trial, but the US-allied government has given this little support.
According to a US affidavit prepared by Habib's American lawyer, his Egyptian captors gave Habib electric shocks and beat him.
"Mr Habib, always handcuffed and sometimes suspended from hooks on the wall, was kicked, punched, beaten with a stick, and rammed with what can only be described as an electric cattle prod," said the affidavit, which was reported on Australian radio.
"If he lapsed into unconsciousness, they would revive him and continue the beatings."
Habib said he was forced into false confessions, such as admitting to training al-Qaida fighters in martial arts.
At times his captors would place him in a room and gradually fill it with water, leaving only his head exposed and forcing him to stand on tiptoe for hours.
In Islamabad, after his capture, a man who had introduced himself to Habib as an Australian consular official watched while a US agent stood on his neck, the affidavit said.