Australia on Thursday said it was preparing to sue ex-Guantanamo Bay inmate David Hicks for the royalties from his tell-all book, claiming they should be considered proceeds of crime. Hicks was captured in Afghanistan after the 9/11 attacks and spent five-and-a-half years in the US-run prison at Guantanamo Bay before being convicted by a military commission of providing material support for terrorism. He returned to Australia in April 2007 and spent nine months in prison completing the commission\'s sentence before finally being freed, on strict conditions that he report to police and not give interviews for a year. Now 35 and living in Sydney, Hicks broke his silence last year with an autobiography detailing his time in Guantanamo and the events that led up to his capture. It has reportedly sold 30,000 copies. \"The Director of Public Prosecutions has applied for a restraining order and a literary proceeds order,\" a government spokeswoman told AFP, adding the case would be heard in the Supreme Court of New South Wales state on August 3. Formerly an outback cattleman and once dubbed the \"Aussie Taliban\", Hicks is not permitted to profit from his book under amendments to Australian proceeds of crime law made specifically to recognise his case. The lawsuit has surprised some legal watchers, who say it will be a test of his conviction by the US Military Commission and could challenge the controversial quasi-judicial system\'s authority in Australia. \"It may well be that this takes twists and turns, and may even up possibilities for David Hicks to gain recognition that his offence was not one that should be recognised under Australian law,\" said constitutional lawyer George Williams. \"He may well (raise) issues going to the nature of his plea, whether duress was involved, whether it was a plea that should be recognised under the Australian legal system, and that could go to quite fundamental questions about the rule of law and the types of proceedings that can be properly recognised under Australian law,\" Williams told ABC radio. He added he would not be surprised if the case ended up in the nation\'s top court, the High Court, to decide \"some quite important matters of principle.\" Hicks\'s memoir \"Guantanamo: My Journey\" describes \"six years of hell\" in the prison in Cuba, where he endured deprivation and witnessed acts of brutality. He details paramilitary training in Afghanistan and Pakistan and involvement in conflicts in Kosovo and Kashmir, but claims he was a \"political scapegoat\" and said he never had extremist intentions. Hicks would not comment on the royalties case but told ABC television in a yet-to-be-aired interview -- excerpts of which were released Thursday -- he would welcome the chance to challenge his conviction in an Australian court. \"I would relish the opportunity, if the government attempted to take my money, because it would mean for the very first time I\'d get to go in front of a real judge, in a real court and to have my case thrashed out,\" Hicks said. \"The government would have to establish that ... I\'d actually breached a law or committed a crime, which has been acknowledged by all sides involved that I didn\'t. \"So I\'d relish the opportunity for that court case.\" His ex-lawyer Stephen Kenny said he doubted an Australian court would rule against Hicks, saying he had pleaded \"to a crime that doesn\'t exist before a tribunal that\'s not recognised by anybody except the Australian government\".