Abbott has challenged the prime minister to reveal what advice he’s been given to support the new counter-terrorism department.

Under the plan, which would come into force next year, a home affairs portfolio headed by Immigration Minister Peter Dutton would cover agencies including the Australian Federal Police, ASIO, Australian Border Force as well as customs and citizenship.

Turnbull has described it as the biggest change in national security for four decades.

Abbott says the issue was raised when he was prime minister but he was advised against it.

“The advice back then was that we didn’t need the kind of massive bureaucratic change which it seems the prime minister has in mind,” Abbott told 2GB radio on Wednesday.

“I can only assume the advice has changed.”

Abbott instead appointed Greg Moriarty as Commonwealth counter-terrorism coordinator within the Prime Minister’s Department.

Moriarty has since been appointed chief of staff to Turnbull.

Turnbull defended the plan on Wednesday night, insisting it was an idea considered by several prime ministers but not proceeded with because of “bureaucratic inertia”.

“You can say, ‘oh, well, if it ain’t broke don’t fix it’ – that’s laziness and complacency,” Turnbull told The Project.

“You can wait until there is a disaster or a crisis and that wakes you up and prompts you into action.

“My approach every day of my life is to try to do my job better.”

Dutton has also doubled down in his defence of the plan, insisting it was the best way to deal with the increasing terror threat.

“I think we can improve. I’m not going to wait for a terrorist incident to take place,” he told Sky News.

– AAP