Australian PM Anthony Albanese says he will investigate reports that his predecessor, Scott Morrison, secretly assumed three roles in the ministry.
Morrison became joint minister for the health, finance and resources portfolios in the two years before he lost power in May, local media report.
The former prime minister has declined to comment.
On Monday, Governor-General David Hurley - the Queen's representative in Australia - confirmed he had signed an "administrative instrument" that had allowed Mr Morrison to secretly take on the portfolios. It was "consistent with section 64 of the constitution", a spokesperson said.
But Mr Albanese, law experts and Mr Morrison's former colleagues have criticised the secrecy surrounding it.
Even some ministers were reportedly not aware they were sharing portfolios with the former prime minister.
"This is the sort of 'tin pot' activity that we would ridicule if it was in a non-democratic country," Mr Albanese told reporters on Monday.
But then-Finance Minister Mathias Cormann - now head of the OECD - only learned last week that his role had been jointly held, said a report by local outlet News.com.au.
Mr Morrison was sworn in as a second resources minister - joining Keith Pitt - last year. Mr Morrison used his powers to block a gas exploration licence in New South Wales - a decision opposed by Mr Pitt.
Mr Albanese said he would not speculate on forthcoming legal advice but accused his predecessor of having governed "in the shadows".
When asked to respond to Mr Albanese's comments, Mr Morrison said he wasn't aware of them. "Since leaving the job I haven't engaged in any day-to-day politics," he told Sky News Australia.
Mr Morrison's deputy from June 2021, Barnaby Joyce, said he did not have prior knowledge of the appointments.
"I found out about it, and I disagree with it. I believe in a cabinet system of government where ministers are responsible for their own portfolio. We don't have a presidential form of government," Mr Joyce told Channel 7.
The centre-right coalition suffered a convincing defeat in May's general election. It lost many seats in cities - where climate action and political integrity were seen as key issues.
In July, Mr Morrison drew controversy by telling churchgoers "don't trust in governments" and "don't trust in the United Nations" during a speech in Perth.