The Iraq War Inquiry Group, consisting of eminent Australians from diverse backgrounds, today launched a call for a high-level independent inquiry into how Australia became involved in the invasion of Iraq.

The launch was hosted by Australian Greens Senator Scott Ludlam, the Member for Fremantle Melissa Parke, and the Member for Denison Andrew Wilkie.

Former Australian Prime Minister Malcolm Fraser, former Secretary of the Department of Defence Paul Barratt, and General Peter Gration (retired), former chief of the Australian Defence Force, spoke of the need to investigate how Australia was committed to an illegal and unprovoked war.

"The Australian public have a right to know how and why this happened, in order that it never happens again," Senator Ludlam said.

"If the power to send Australian soldiers to war rested with the Parliament, and not the Prime Minister alone, in 2003 - we would not need this inquiry now."

The Greens war powers bill, initially introduced by the Australian Democrats two decades ago, would make the final decision to commit Australia to war a matter for the Parliament, not the Cabinet.

The Iraq War Inquiry Group has produced a wide-ranging issues paper making the case for an inquiry.