Scott Morrison’s decision to secretly take on extra ministerial portfolios while he was prime minister has been labelled corrosive of trust in government.

A report by former High Court judge Virginia Bell into the multiple ministries found the secrecy surrounding the appointments Mr Morrison covertly adopted was “apt to undermine public confidence in government”.

“Once the appointments became known, the secrecy with which they had been surrounded was corrosive of trust in government,” the report, released on Friday afternoon, said.

“Given that the parliament was not informed of any of the appointments, it was unable to hold Mr Morrison to account in his capacity as minister administering any of these five departments.”

The report also revealed that Mr Morrison had eyed off appointing himself to a sixth portfolio. Briefs were prepared for him to be named as agriculture, water and environment minister, before he decided not to go ahead with that appointment.

Ms Bell recommended six changes following the report, including implementing legislation requiring public notifications of the appointment of ministers.

She also recommended publishing details of which ministers were appointed to administer departments and outlining different responsibilities when more than one minister was appointed to the same department.

Prime Minister Anthony Albanese said he would recommend cabinet implement all six recommendations.

“The quick implementation of these recommendations will ensure that the Australian public can have full confidence that this breach of trust will never happen again,” he said.

“The unprecedented and inexcusable actions of the former prime minister were emblematic of the culture of secrecy in which the previous government operated.”

Asked if Mr Morrison should resign from parliament, Mr Albanese said “a whole lot of people need to look at their behaviour in this”.

“The actions of the former prime minister were extraordinary. They were unprecedented, and they were wrong,” he said.

Mr Albanese said Mr Morrison’s “inexcusable actions … were emblematic of the culture of secrecy in which the previous government operated”.

He said Mr Morrison did not meet with Ms Bell while she worked on the report, and communicated only through his lawyers.

“That contradicts the very clear statement that Morrison said when this inquiry was announced. And I think that will come as a surprise to people who took those comments at face value,” Mr Albanese said.

“Justice Bell described Morrison’s various accounts for his conduct as ‘not easy to understand and difficult to reconcile.”

Mr Morrison responded to the report with a lengthy statement on Facebook on Friday.

“I was pleased to assist the inquiry with six separate and comprehensive responses to matters raised with me and my legal representatives by [Ms Bell]. This engagement was done via correspondence, as was the practice with other respondents to the inquiry and accepted [Ms Bell],” he wrote.

“I note the criticisms made of my decision to be authorised to administer a series of departments where ministers had specific powers not subject to the oversight of Cabinet. These decisions were taken during an extremely challenging period, where there was a need for considerable urgency. I note that the criticisms of my decisions have been made after the event and with the benefit of this perspective.”

Mr Morrison appointed himself minister of the departments of health, finance, industry, science, energy and resources, treasury and home affairs, without the knowledge of most of the appointed ministers.

On Friday, former treasurer Josh Frydenberg broke his silence on the ministries scandal, saying he felt “angry, hurt, confused, dumbstruck” after finding out via social media about the secret appointments.

Mr Frydenberg told author and Nine newspapers columnist Niki Savva his former leader still hadn’t apologised for his actions.

“I don’t think there was any reason for Scott to take on the additional Treasury portfolio,” he told Savva, according to an extract from her upcoming book on the Morrison regime published on Friday.

Mr Frydenberg called Mr Morrison’s actions “extreme overreach”.

He was backed up by former finance minister Simon Birmingham, who said there was no need for Mr Morrison to take on portfolios beyond health and possibly finance.

“People can understand the initial decisions as it relates to health and even possibly finance taken at the absolute height of concern around the COVID pandemic,” Senator Birmingham said.

“The latter decisions were a form of overreach and there’s not necessarily a clear explanation.”

Mr Morrison’s takeover of the health and finance portfolio roles began in March 2020, while he started as industry minister in April 2021, and home affairs and treasury in May 2021.

He has justified his actions by saying the only time he used his extra powers was in vetoing the PEP11 resource exploration project off the NSW coast.

Mr Morrison has said he intended the powers to be used only in extreme circumstances “due to incapacity or in the national interest”.

Mr Albanese asked Ms Bell to inquire into the scandal after the solicitor-general found Mr Morrison’s action had “fundamentally undermined” the principles of responsible government. Mr Morrison was not found to have broken any laws with his actions.

Mr Albanese asked for the inquiry to explore how and why the steps were taken, and who knew about them.

The solicitor-general found it was “impossible for the parliament to hold ministers to account for the administration of departments if it does not know which ministers are responsible for which departments”.

Deputy Liberal leader Sussan Ley dismissed reports the Coalition had determined to downplay the severity of Mr Morrison’s actions and said it would support closing the loophole that was exploited.

-with AAP