Department of Prime Minister and Cabinet refers Plagued, which revealed Scott Morrison's secret ministries to the Attorney-General's Department

Speaking to senate estimates on Friday, the Department of Prime Minister and Cabinet also revealed it did not know the former prime minister was briefing the book's authors throughout the COVID-19 pandemic.

The book - Plagued, written by NewsCorp journalists Simon Benson and Geoff Chambers - touted exclusive access "behind doors normally sealed", revealing Mr Morrison had assumed control over five powerful ministries without the knowledge of the vast majority of his colleagues or the public.

And PM&C acting deputy secretary John Reid warned other published details, including on the Morrison government's response to China and pursuit of the AUKUS deal, could harm Australia's international relationships.

Under questioning from Labor senator Tony Sheldon, Mr Reid confirmed the book appeared to contain leaks "directly concerning" the National Security Committee, national cabinet, and cabinet.

He said the Department had referred it to the Attorney-General's Department.

"Our conclusions were that it certainly appears to reveal information that was, until revealed, cabinet material, and would ordinarily have been protected under the principle of cabinet confidentiality," he said.

The review was prompted by reporting on the book, and not at the direction of Prime Minister Anthony Albanese' office, Mr Reid said.

"It seemed appropriate that we should we should have a look at it," he said.

"I don't think it's something that happens regularly. It's not something that's generally consistent with the principles of cabinet confidentiality that have been observed."

Senator Sheldon accused Mr Morrison of prioritising "ego over national security" by providing information to the journalists.

"It's concerning [sensitive information] ... is being bandied around through a book [and] unprecedented access to journalists, even in the prime minister's own words," he said.

Mr Reid said the department would "absolutely" cooperate with any criminal investigation arising from the referral, but said he was not aware of the A-G's Department referring the matter to police.

Commonwealth officials who leak from cabinet can jail time under laws against unauthorised disclosure of cabinet information.

No minister has ever faced a prosecution under those provisions.

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He refused to be drawn on whether Mr Morrison had failed to ensure sensitive cabinet information was not leaked.

"Obviously, governments have generally observed the strong convention that cabinet deliberations such as those do and should remain confidential," he said.

"[But] it is a matter for the prime minister of the day to decide that various information ought to be released."

Mr Reid revealed the department was not aware that Mr Morrison was providing exclusive briefings to the two journalists as the government grappled with the COVID-19 pandemic, an escalating trade stoush with China, and Russia's invasion of Ukraine.

After Liberal senator Simon Birmingham accused her of not being forthcoming with information, Foreign Minister Penny Wong took aim over the secret ministries scandal.

"We're certainly not going to be having committees of one, or the multiple ministries that we all know about, or prime ministers talking about what happened in national security committee meetings to journalists," she said.

"So there are a few benchmarks there that I think are pretty low."

In August, Mr Morrison apologised to colleagues for not informing them of his secret power grab, but insisted he was "steering the ship in the middle of the Tempest".

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