Former prime minister John Howard's assertion that he he "couldn't believe it" when it was revealed that the late Iraqi dictator Saddam Hussein did not possess any weapons capable of mass destruction has raised the ire of former intelligence officer Andrew Wilkie.

Mr Howard confessed to feeling "embarrassed" when the intelligence failure was made public, undermining support for the US-led invasion of Iraq in 2003, to which he committed Australian troops.

"If I had been against sending troops they wouldn't have gone but I was in favour of them going and so were all the members of the National Security Committee," he told the Seven Network on Sunday.

Asked about his reaction to revelations Iraq did not have weapons of mass destruction as the US president George W. Bush had claimed, Mr Howard said he "felt embarrassed" by the news.

"I did, I couldn't believe it, because I had genuinely believed it," he said.

Mr Howard said he was "struck by the force of the language" in the US intelligence that judged Iraq did have WMD and a potential nuclear capacity but said it was wrong to claim the intelligence had been cooked up to justify the invasion.

"I did my best to explain it wasn't a deliberate deception … it may have been an erroneous conclusion based on the available information but it wasn't made up and the suggestion that Bush made it up is nonsense," he said.

Independent MP Andrew Wilkie, who at the time worked at the Office of National Assessments, quit the Australian intelligence agency and blew the whistle on the exaggerated intelligence.

"John Howard should be feeling a darned sight more than embarrassed, he should be feeling quite ashamed of himself," Mr Wilkie told the ABC on Monday.

"He should be feeling quite lucky that he hasn't been charged with conspiracy to commit mass murder."

Mr Wilkie argued Mr Howard had conveniently left out ONA assessments which explored Washington's thinking at the time and the United States' reasons for wanting to go into Iraq.

"This is a case of him cherry-picking."

Mr Howard said it was a "false reading of history" to suggest the recent rapid rise of extremists in Iraq, which Australia has committed to fighting via air strikes, are related to the Second Gulf War.

Mr Howard also said the terrorism threat in Australia "is real".

"I don't think any Australian should assume we won't have a terrorist event here," he warned and urged the community to work harder at integrating people of different races and religions into mainstream Australia.

Mr Howard linked the growing trend of disaffected Australian Muslims joining Islamic State extremists overseas to "closed communities" existing across the country.

"As many people know, I'm not an overwhelming fan of the doctrine of multiculturalism," Mr Howard said.

Mr Howard also said it would not be a good idea to restart a debate about levels of Muslim immigration.

"Apart from anything else, it would be seen among friends such as Indonesia and Malaysia as a negative thing," he said.

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