John Howard should be tried for conspiracy to commit mass murder by the international criminal court over the 2003 invasion of Iraq, independent MP Andrew Wilkie has claimed.

Wilkie said he was aware of the seriousness of the allegations he was making which were prompted after Howard told Seven Network’s Sunday Night program that he was “embarrassed” no weapons of mass destruction were ever found in Iraq.

“I was shocked to see that John Howard is only embarrassed, almost embarrassed for himself. What he should be is deeply ashamed that he lied to the Australian public 11.5 years ago, and took us into an unnecessary war, a war that has killed countless Iraqis and other people, which effectively destroyed that country and created the conditions for the rise of not just the Islamic State but other groups,” Wilkie told reporters in Canberra.

“Look frankly I’m disappointed that the prosecutor at the international criminal court hasn’t thought to hold John Howard responsible for conspiracy to commit mass murder.”

He said he did not “take the statement lightly at all” but believed many Australians agreed with him.

Howard addressed the broader issues of the Iraq war and Islamic State (Isis) on Sunday Night and rejected arguments the 2003 invasion was a major factor in the growth of (Isis).

“I felt embarrassed, I did, I couldn’t believe it, because I had genuinely believed it,” he said on revelations Iraq did not have weapons of mass destruction.

Howard said he was embarrassed but it was not 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

Howard said he was struck by the “force of language” used in the American national intelligence assessment in 2002 and “paragraph after paragraph” it said Iraq had WMDs.

Howard argued the 2003 invasion did not play a major role in the rise of Isis which now holds large swathes of Syria and northern Iraq.

“If you’re seeking to locate the responsibilities [for the situations in Iraq and Syria] specifically to the 2003 invasion, let me put to you Syria was not involved in any outside military operation,” he said.

“ ... so much of the Islamic State operation comes out of what is occurring in Syria, and to suggest that it’s purely or predominantly a result of what happened in Iraq in 2003 is a false reading of history.”

Wilkie said Howard should have made a “compelling humanitarian” case for dealing with Saddam Hussein in 2003 and told the voters the invasion was about Australia’s bilateral relationship with America, not WMDs.

When asked again if he was suggesting Howard was partly responsible for the rise of Isis, Wilkie responded “I’m not suggesting it, I’m stating it as fact”.

“The circumstances in Iraq today are a direct result of the anarchy and the security vacuum that was created, that has been created in this country as a result of 11.5 years of war, a war that was started in part by the Australian government and John Howard in particular,” he said.

“If we had not gone to war 11.5 years ago, and destroyed that country and created this security vacuum, then the circumstances would not exist for Islamic State to have emerged and to grown strong and to conquer the land that it does. So yes, they are responsible.”

Wilkie said he was not excusing Isis, as what they were engaged in was “unforgivable”.

A spokesman for Howard dismissed Wilkie’s claims as “absurd”.