The bipartisan committee cleared the government of "sexing up" intelligence to justify war against Iraq but recommended a review of the intelligence agencies, particularly its Office of National Assessments (ONA), which advises the prime minister.

The ONA, it said, had made a sudden and as yet unexplained change in its assessments between September 12 and 13, 2002, when it appeared "more ready to extrapolate a threatening scenario from historical experience."

Government MP David Jull, who chaired the committee, said the changes meant the ONA "overstated" the threat posed by Iraq's weapons of mass destruction (WMD) compared to assessments made by another spy agency, the Defence Intelligence Organisation. "The government's emphatic claim about the existence of Iraqi WMD reflected the views of the ONA after 13 September 2002," he said.

Jull told the national parliament Australia's intelligence agencies faced a difficult job in assessing Iraq's weapons capability, but it was now clear some of their judgments were wrong.

"Our conclusion was that the assessments of the Australian intelligence community were more moderate and cautious than those of the partner agencies in the US and the UK," he said.

"However, despite their caution, it's possible they overstated their case."

Howard, like US President George W. Bush and British Prime Minister Tony Blair, based his decision to join the invasion of Iraq on the claim that its president Saddam Hussein possessed and was prepared to use stockpiles of WMD.