Morrison is resisting calls by his former colleagues and others to quit parliament after news of the extraordinary appointments broke, telling a long and rowdy press conference on Wednesday that only he knew the weight of responsibility that the Covid-19 pandemic bestowed on his government.

Albanese revealed on Tuesday that Morrison had appointed himself to the finance, treasury, health, home affairs and resources portfolios between March 2020 and May 2021 but had not told his Cabinet colleagues.

One of Morrison’s decisions as resources minister – in relation to the PEP-11 gas project off the NSW coast – is before the Federal Court.

The solicitor-general is preparing advice for Albanese to be delivered on Monday on whether there are other legal issues at play relating to Morrison’s actions.

The prime minister told journalists in Brisbane that Morrison has effectively led a “shadow government”.

He said that after listening to Morrison’s justification for his actions before the Sydney press conference, the former prime minister was “evasive, he was defensive, he was passive aggressive and he was self-serving. So at least he was true to himself today.”

However, both he and Morrison would not brook criticism of Governor-General David Hurley for his role in accepting the secret ministerial appointments.

“The government of the day has to accept responsibility for this and the people who were involved in it directly have to accept responsibility,” he said.

Morrison told reports: “I believed it was necessary to have authority, to have what were effectively emergency powers, to exercise in extreme situations that would be unforeseen, that would enable me to act in the national interests.”

“Where there were authorities or powers that could be established, there was a clear expectation that I, as prime minister, would have sought to put those in place to protect the country and lead us through what was a very difficult period.”

Morrison added the lawful move wasn’t a power grab as he never used the powers or overruled ministers, apart from the resources portfolio decision.

“As prime minister, only I could really understand the weight of responsibility that was on my shoulders,” he said.

“The non-exercising of these powers proves that they were handled responsibly, that they were not abused, that they were there in a reserve capacity to ensure the prime minister could act if that was necessary.”

Morrison says he kept the powers a secret to not undermine his ministers and create a misunderstanding.

“I was concerned these issues could have been misconstrued and misunderstood and undermine the confidence of ministers in the performance of their duties at that time,” he said.

“To best of my recollection … I didn’t exercise any override of any of the ministers in any of their agencies except for (PEP-11).”

One of Morrison’s former ministerial colleagues, Karen Andrews – who was unaware she was being shadowed in her role by the Liberal leader – has called on him to quit parliament.

A number of crossbenchers have flagged referring Morrison to parliamentary committees.

He said he was happy to cooperate with any “genuine or positive process” that examined the government’s pandemic response.

He apologised to his colleagues for having secretly sworn himself into their portfolios but launched a staunch defence of his actions, saying the Covid-19 pandemic required a unique response.

“It was a very extraordinary time that tested every sinew and fabric of government, not just at a federal level but at a state level as well and indeed tested the very fabric and sinew of Australian society,” he said.

“We took decisions – I did as a prime minister, we did as a cabinet – at federal and state level that some of us would never have dreamed that we would ever have to make.”

But constitutional lawyer Anne Twomey says legal systems were already in place, with acting ministers able to be appointed when a minister is sick or on leave.

“It seems there’s this presidential view of, ‘Hey, I’m the leader, therefore I must have responsibility for everything’,” she told Sky News.

“That’s a real denial of the actual system of government we’ve got. The prime minister, at most, is the first amongst equals.”

Labor is considering ways to make ministerial appointments more transparent.

Albanese said the actions of his predecessor followed a pattern of secrecy.

“Our democracy relies on people being open and transparent about what’s going on (and) people being accountable and that’s why this is such a shocking series of revelations,” he told radio 4BC.

Deputy Liberal Leader Sussan Ley attacked the prime minister for not focusing on the cost of living and skills shortages.

“Australians want him to focus on the issues in their lives. Nothing in this is going to bring down your power bills,” she told Sky News.

Home Affairs Minister Clare O’Neil said intelligence chiefs were unaware of Mr Morrison’s self-appointment to the important role.