As the new Labor government investigates what high-ranking bureaucrats knew about Mr Morrison's additional ministerial portfolios, the Home Affairs Department confirmed its secretary Mike Pezzullo did not know the then-prime minister had assumed powers to administer the department.

It is also understood that Treasury secretary Steven Kennedy was not aware of Mr Morrison's appointment to administer the Department of the Treasury.

Prime Minister Anthony Albanese on Tuesday excused public servants for not publicising the unknown additional powers, saying it was for politicians to reveal Mr Morrison's appointments.

Mr Albanese has said he expects to learn more about the extent of senior public servants' knowledge of Mr Morrison's portfolio roles, but told journalists that more than one official from the Department of the Prime Minister and Cabinet knew about them.

The departments of Health and Industry, Science and Resources deferred questions about the saga to the Prime Minister's Department, which is advising Mr Albanese about the secret appointments.

When asked whether department secretaries and other public servants were informed that Mr Morrison was their minister, PM&C said: "The Prime Minister has asked the secretary of the Department of Prime Minister and Cabinet to provide advice on this matter."

A Home Affairs Department spokesperson said Mr Pezzullo was not aware Mr Morrison had been sworn in to administer the department. It is understood Dr Kennedy, who leads the Department of the Treasury as secretary, has confirmed he had no knowledge of the former prime minister's appointment to the portfolio.

Morrison government home affairs minister Karen Andrews, who called on Mr Morrison to resign from parliament and said he had betrayed the trust of the Australian people by his actions, questioned the decision not to tell public servants about the portfolio roles.

"How can a new minister be sworn into a portfolio without the bureaucracy being told about it or know about it? I mean, that just opens up a whole range of questions," she told The Canberra Times.

Mr Albanese earlier revealed the Prime Minister's Department had advised him that his predecessor had assumed power to administer several departments including Health and Finance starting in March 2020, Treasury and Home Affairs from May 2021, and the then-Department of Industry, Science, Energy and Resources from April 2021.

Mr Albanese has asked the Prime Minister's Department to advise him on Mr Morrison's additional roles, and also expects a briefing from the Solicitor-General on the legality of the arrangements by Monday.

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He cleared public servants of blame over the secrecy on Tuesday morning, saying politicians were the decision makers.

"They're the ones that need to be held to account here. The politicians who made these decisions and who asked, obviously, at the time, they asked that this information be kept secret," Mr Albanese said.

"It's not up to public servants to release this information. It was up to the decision makers who were the elected representatives."

Mr Morrison released a statement saying he had acted in good faith in response to the pandemic, and that most of the arrangements were intended as a safeguard against ministers falling ill with COVID.

"It is important to note that throughout this time ministers in all departments, where I was provided with authority to act, exercised full control of their departments and portfolios without intervention," he said.

Mr Morrison said he decided to assume power to administer the then-Department of Industry, Science, Energy and Resources to consider the PEP11 gas exploration licence directly.

- With Karen Barlow