Leading Australian politicians and former defence chiefs are demanding an independent investigation, along the lines of the Chilcot inquiry in Britain, into their country's role in the invasion of Iraq.

They say an independent inquiry must investigate the circumstances that led the then National-Liberal coalition to participate in the US-led invasion in 2003 in which Australia contributed 2,000 troops, including special forces. It must also conduct a review of the war powers of the government, and draw lessons for the future.

Demands for an inquiry are led by former Liberal prime minister, Malcolm Fraser, former defence secretary, Paul Barratt, and former chief of the Australian Defence Force, General Peter Gration.

In a foreword to the publication "Why did we go to war in Iraq? A call for an Australian inquiry", which says Australia was exposed to the accusation of waging an illegal war, Fraser writes that an inquiry would not rake over old coals but rather "develop a better understanding of how warfare decisions are reached and to strengthen the governmental structures against precipitous or ill-considered actions in future."

The call for an inquiry is also supported by a statement signed by 30 leading academics in politics and law, retired senior diplomats and experts in the field of war and conflict.

"In retrospect", Fraser writes, "what we now see were frantic efforts to create the prerequisites by manipulating intelligence assessments to fit the case, with all the sophistication that task required. The general public had become confused as to whether the weapons of mass destruction allegedly being developed or held by Saddam Hussein existed and were being placed in a state of readiness to justify both 'national interest' and 'self-defence' claims."

He adds: "In all this, the Australian government may have thought it had no choice if it were to retain the confidence of the US. But was this a misjudgement? [...] Did the government really think through the issues independently and the implications for our standing with Asian neighbours? Did it really evaluate the intelligence presented to it and ignore its flaws? Did it want to? Did it really consider the legal issues surrounding the proposed invasion objectively, or was it not really interested?"

The Australian parliament's role in war is merely "ex post facto, to approve actions already taken under the prerogative at a stage where the denial of finance would in effect betray the armed forces", say those calling for an inquiry.

They note that the justifications given by US and British leaders for the invasion, which Australia accepted, "were later shown to be based on false information, on which Australia apparently relied".