A group of federal MPs and former military chiefs is ramping up calls for an inquiry into the decisions that led to Australia joining the US invasion of Iraq in 2003, with some pushing to change the war powers invested in the Prime Minister and Cabinet.

Key points: Prime Minister and Cabinet can decide whether to send troops to war

Prime Minister and Cabinet can decide whether to send troops to war Call to broaden powers so parliament must also vote on decision

Call to broaden powers so parliament must also vote on decision Some MPs and former military chiefs also want inquiry into Iraq War

Currently, the Prime Minister and Cabinet can decide whether or not to send Australian soldiers to war, but some want to broaden those powers to a parliamentary vote.

Just a month after Britain handed down the Chilcot Inquiry into the Iraq War, there are also calls for Australia to hold a similar investigation.

Britain's seven-year inquiry found the UK joined the US-led military action before peaceful alternatives to war had been exhausted.

Labor MP Mike Kelly, a distinguished former Army Veteran, says now is the right time to revisit Australia's role in the conflict.

"It's not too late. In fact I think some distance now behind us will give us an even better perspective and better opportunity to do that analysis properly," he told Lateline.

"The whole strategic lead-up, the planning, how we engaged with our allies, how we conducted and executed the mission. There's so much to be teased out about that and in particular the intelligence processes."

Former Australian Army Officer James Brown said in Australia, the learning process was only halfway done.

"I think we're unlikely to see an inquiry as forensic and extensive as Chilcot in Australia but it would be good to see more on the public record about how some of these decisions were made," he said.

Now an Adjunct Associate Professor at the US Studies Centre at Sydney University, James Brown said there is a trend in Western nations towards broader participation in decisions about war, particularly through parliamentary approval.

"That's why we're seeing calls for war powers reform in Canada, New Zealand and particularly in the United Kingdom," he said.

Call for more to have say in going to war

Both major parties support the current war powers arrangement, but Labor Senator Lisa Singh has broken ranks, claiming the decision to go to war is too important to be left solely to the Prime Minister.

"We're talking about one of the most important policy areas that our country has to face. And yet the decision is made by one person," she said.

"Our parliamentarians are intelligent enough, sophisticated enough to work through a system that would work."

But many military strategists disagree, including the executive director of the Australian Strategic Policy Institute (ASPI), Peter Jennings.

"If you look at how parliaments are structured, you're really saying that you're going to leave decisions to go to war to a handful of crossbenchers in the Senate," he said.

"So if we were to have a debate today about deploying, that means it's going to be Jacqui Lambie, Pauline Hanson and her supporters. It's going to be Nick Xenophon. Are they the people we want to give Australia's war powers to?" he asked.

'Don't rake over coals, keep decision-making secure'

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Deputy Prime Minister Barnaby Joyce has rejected the idea of broadening the decision-making process to go to war beyond the Prime Minister and Cabinet.

"These decisions have to be made in an incredibly secure environment; they have to be made in such a way obviously that the enemy does not know what you are up to," he told ABC News Breakfast.

"It has to be made with some immediacy.

"A parliamentary debate whilst your national security is at threat is a rather peculiar concept and I don't agree with it."

Joyce also dismissed the idea of an inquiry into Australia's involvement in the Iraq war.

"The issue now is we've got to realise people make decisions on the information that's presented to them, and that decision was made," he said.

"I don't know whether going back and deciding to rake over the coals there is going to be better than trying to make sure we deliver on our security needs as they stand right today."

War widow calls for reform

Kellie Merritt, whose husband was killed in the Iraq war, has renewed her push for reform of war powers.

Flight Lieutenant Paul Pardoel died when the British Hercules he was flying in was shot down over Iraq.

Flight Lieutenant Paul Pardoel was killed in the Iraq war. ( Supplied )

"We invaded another country and the fallout from that has been catastrophic," she said.

In the lead-up to the 2003 invasion, there was lengthy debate in the Australian Parliament, but the decision was made by John Howard and his Cabinet, without any vote.

"The gravest decision a government can make must also be the most robust, considered, rationally grounded one and the process we have now hasn't leant itself to giving us that sort of outcome," Ms Merritt said.

The Greens plan to reintroduce a bill to debate war powers when Parliament returns next week.

Senator Peter Whish-Wilson said the current system is broken.

"Australia is one of the last Western democracies that can send its citizens to overseas conflicts without any recourse to Parliament," he said.

"The laws and legislation in place now that give essentially full control to the prime minister and the executive date back to the feudal times of royalty."