Liberal MP Stuart Robert attempted to intimidate public servants following media allegations of the former minister's dealings with a consulting firm, parliament has heard.
The allegations date back to when the coalition government was in power and his tenure as a government backbencher and later as a minister.
Mr Robert was a backbencher in 2017 and 2018 and was appointed assistant treasurer in 2018 and then minister for the National Disability Insurance Scheme and government services in 2019.
The Nine newspapers reported on Thursday consulting company Synergy 360, owned by a friend of Mr Robert, claimed in leaked documents the minister met the firm about government contracts.
NDIS and Government Services Minister Bill Shorten said the revelations were concerning.
Parliament was told investigations had shown one of Synergy's clients Infosys had been awarded four contracts totalling $274 million to upgrade payment software within the Department of Human Services.
Talking about the allegations in parliament on Thursday, Mr Shorten revealed public servants had been intimidated.
"I remind members of parliament and the member for Fadden (Mr Robert) after an unfortunate development this morning, please come through my office if you have any requests of the relevant agencies," Mr Shorten told parliament.
"Do not do what you did this morning and inappropriately task and pressure public servants who are no longer your ministerial responsibility."
Mr Robert rejected the "implied imputation" of the media reports "in the strongest possible language".
"I reiterate that all departmental procurements were run with the highest levels of probity," he said on Thursday.
"I had zero involvement with this procurement or any other procurements and reject completely these accusations."
Mr Robert said the project tender referred to by Mr Shorten was released 12 months before he was sworn in as a minister.
He admitted he had written to the head of Services Australia on Thursday morning to "request that she provide probity confirmation".
Mr Robert made the request so that he could provide a response to parliament "as is appropriate".
Last month, The Age and The Sydney Morning Herald cited leaked emails to allege Mr Robert had helped Synergy 360 in 2017 and 2018 sign corporate clients to help it navigate the public service and political system and meet key decision-makers.
Public sector union national secretary Melissa Donnelly said she was concerned about the alleged behaviour.
"No public servant should ever be pressured by a member of parliament and any suggestions of this occurring are deeply concerning," she said.
Mr Shorten said a joint review into the matter would take place, overseen by someone working across Services Australia and the National Disability Insurance Agency.
He said the arrangement would ensure there was no real or perceived conflict of interest for agencies to investigate themselves.
"It'll provide important independence to get to the bottom of the matter whether there was any misconduct," Mr Shorten said.
"Australian taxpayers and voters have the right to know whether there's been any impropriety, equally to be assured that government contracting processes are independent and merit-based and not swayed by special interests or lobbyists."
Mr Robert welcomed the review and any processes the minister saw fit to ensure transparency and accountability.