The former prime minister has defended keeping the multiple portfolios secret, saying they were a safeguard and that he would have made them public had he needed to use the powers involved.

"Sometimes we forget what was happening two years ago and the situation we were dealing with; it was an unconventional time and an unprecedented time," he told Sydney radio station 2GB on Tuesday.

"Boris Johnson almost died one night. We had ministers go down with COVID."

The ex-Liberal leader's comments came as Prime Minister Anthony Albanese revealed that between March 2020 and May 2021, Mr Morrison was appointed to five additional portfolios.

They included health, finance, home affairs, treasury and industry.

"This is a sad indictment of not just Mr Morrison but all those cabinet colleagues of his, who sat back and allowed this to happen," he said.

"It's undermined our democracy. It's an attack on the Westminster system of parliamentary democracy as we know it.

"And not just Mr Morrison but others who were involved in this need to be held to account."

Mr Albanese said he had asked for advice from the solicitor-general on the impacts of Mr Morrison's actions.

"We know that there is a legal matter in the issue of resources," he said.

"I am seeking further advice as to the use of these extraordinary powers by Scott Morrison and other examples of it."

Mr Morrison called the actions "a two key approach".

"We had to take some extraordinary measures to put safeguards in place," he said.

"Fortunately, none of these in the case of the finance and health portfolio were ever required to be used.

"The powers in those portfolios, they weren't overseen by cabinet. The minister ... in both cases had powers that few, if any, ministers in our federation's history had."

Mr Morrison said he didn't recollect other ministries he took on outside health, finance and resources, but documents reveal he also took on aspects of the social services portfolio.

"No, not to my knowledge no," Mr Morrison said when asked directly if he was sworn in as social services minister.

Mr Morrison clarified his position minutes later, saying: "I don't recall that but I mean, as I said, there was some administrative issues done. I don't dispute that."

An administrative arrangements order for the social services portfolio was signed by Mr Morrison and Governor-General David Hurley on June 28, 2021, on top of him being privately sworn in to other ministries.

Mr Morrison said all actions were taken to ensure the "buck stopped with the prime minister" as he had no legal powers to directly order a minister to take a certain decision.

"If I wished to be the decision maker, then I had to take the steps that I took," he said of a call to overrule resources minister Keith Pitt on a controversial NSW gas project, PEP-11.

"People know where the buck stops and the buck stops with the prime minister. I sought to be the decision maker on that issue because of its importance."

Mr Morrison says his failure to inform then finance minister Mathias Cormann he had been sworn into his portfolio was a regrettable oversight, thinking the information had been passed on through offices.

Mr Pitt says he was unaware Mr Morrison had joint oversight of his portfolio but stands by the decisions he made.

A spokesperson for Governor-General David Hurley says he followed processes consistent with the constitution when he appointed Mr Morrison to the additional portfolios.

"It is not uncommon for ministers to be appointed to administer departments other than their portfolio responsibility," the spokesperson said in a statement.

Such appointments do not require a swearing-in ceremony but rather the governor-general signs an administrative instrument on the advice of the prime minister.

Opposition Leader Peter Dutton said he didn't know Mr Morrison had sworn himself into the cabinet positions.

Australian Associated Press