Former prime minister Tony Abbott says he was told there was no need for a Home Affairs Ministry when he was in office, casting doubt on the biggest national security shake-up in decades.

Mr Abbott indicated support for such a ministry last month, saying he did not want "turf-protecting ministers" to stand in the way.

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The latest interjection by Mr Abbott, who said he had a duty to comment on national affairs as a former prime minister, added to concerns the super-ministry may not be necessary.

On Tuesday, Prime Minister Malcolm Turnbull announced Immigration Minister Peter Dutton would lead the super-ministry, adding ASIO and the AFP to his responsibilities.

Mr Abbott said he considered making the change but decided against it.

"The advice back then was that we didn't need the kind of massive bureaucratic change that the Prime Minister has in mind," he told Sydney radio station 2GB.

"I can only assume the advice has changed since then and no doubt the Prime Minister will give us more information in due course."

This may be a surprise to Mr Dutton, who told the ABC that Mr Abbott supported the change.

"I know from my discussions with Tony, when he was prime minister, he supported the concept of a Home Affairs Office," Mr Dutton told ABC's 7.30.

When asked about Mr Abbott's comments on Wednesday, Mr Dutton said he had different advice and would not be distracted by "white noise".

In June, Mr Abbott told 2GB he was worried ministers resisting change would stop, "the best possible counter-terrorism arrangements".

"I can see the argument for a Home Office," he told 2GB at the time.

"I could see the argument for a Home Office-type situation, arrangements when I was prime minister."

Mr Dutton and the Prime Minister said the super-ministry was necessary along with an overhaul of intelligence arrangements, but security experts are not convinced.

John Blaxland from the Australian National University warned against tampering with a system that was "arguably the envy of the world".

Sorry, this video has expired PM Malcolm Turnbull announces new Office of National Intelligence

Mr Abbott said Mr Dutton, a senior conservative figure in the Turnbull Government, was the perfect pick for the role.

"I can think of no better person than Peter Dutton to be the minister, it seems he is going to have to wait many months to be the minister," he said.

"He has done an outstanding job as Minister for Border Protection and I know he will do this job well when it is finally clarified."

I have the PM's number and a duty to speak: Abbott

Mr Abbott also sidestepped comments by the new Liberal Party president Nick Greiner, who asked him to sit down with Mr Turnbull and "be adults".

Mr Greiner warned the long-standing feud and displays of public disunity could cost the Coalition the next election.

Deputy Prime Minister Barnaby Joyce also raised concerns that infighting could be costing votes in Queensland, with disaffected voters turning to One Nation.

Mr Abbott said he talked with the prime minister when he needed to.

"As for myself and Malcolm, we've got each other's phone numbers and we make the relevant calls as it should be," he said.

"When we need to talk to each other, we do, that's what happens between members of political parties.

"As a former prime minister I have not just a right but a duty to speak out when I think it's important."

Back in 2008, Mr Turnbull said a proposal to create a similar ministry was "a very poorly perceived idea" and "a wasteful and costly exercise in bureaucracy".

When announcing the ministry, the Prime Minister said the threat posed by terrorism had changed significantly in recent years and Australia could not risk a "set and forget" attitude.