On Thursday Fairfax Media revealed that as many as 50 IT subcontractors were under investigation in a fraud probe at the government's largest department.

The allegations related to fake invoicing practices and the use of false CVs and qualification records to secure government contracts.

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Linda Burney, Labor's human services spokeswoman, and Ed Husic, their digital economy spokesman, said Human Services Minister Alan Tudge must front up.

"The minister that brought us the robo-debt debacle has questions to answer about reports of massive tech contractor fraud that occurred right under his watch," they said in a joint statement.

"It also highlights that Labor was right to push for a Senate inquiry into the management of digital transformation projects under the Turnbull government's watch."

The fraud allegations were proof the government had "lost a grip on managing its ICT projects," they said.

At least one DHS employee is also under suspicion and the department has called in the Australian Federal Police to help with the investigation.

Rory Markham, the employment litigation director at Chamberlains Law, said many of the subcontractors were surprised to learn of their alleged role in the breaches.

"Some of the employees involved in the claim now have reason to believe that, without their knowledge, they had CVs submitted on their behalf that were false," said Mr Markham, who is acting for 10 of the employees.

"These are mums and dads with mortgages to pay and kids to feed. And they are not getting paid while these claims are investigated."

A spokeswoman for the Department of Human Services confirmed the investigation when approached on Wednesday.

"The Department of Human Services is conducting an internal investigation into allegations of potential fraudulent behaviour involving a small number of former contractors and an APS employee," she said.

"The department is being provided support and assistance by the Australian Federal Police.

"As this investigation is ongoing, it would not be appropriate to provide any further comment at this time."

Google search records show that the department updated the "Reporting Fraud" section of its website earlier this week.

The subcontractors had their passes confiscated last Thursday and Friday.

"I witnessed the eviction. The first day nine people were evicted with several pretty heavy security guards," said one DHS source.

"The second day another six were evicted."