Tens of thousands of fraudulent flood assistance claims have been made this year, with more than $10 million dollars in support denied.
Payments have been offered to people impacted by floods in New South Wales and South-East Queensland in February and the recent Sydney floods in July.
Government Services Minister Bill Shorten has raised concerns that, while money is being offered to those who need it, others are taking advantage of the system.
"I believe that the taxpayer-funded safety net needs to go to those who need it and it really makes my blood boil when I think that there are some people out there taking advantage of other people's misery to steal $1,000," he said.
"What is going on with people? How can people think like that?"
The support on offer includes the Australian Government Disaster Recovery Payment of $1,000 per adult and $400 per child, as well as the Disaster Recovery Allowance which provides 13 weeks of support at the rate of the JobSeeker allowance.
About 3.5 million claims have been made for assistance between February and July following the floods.
Of those, there have been 27,770 cases that appear to be suspicious and about $10.5 million in support has been denied.
Mr Shorten said it was important that all fraudulent claims were picked up by the system.
"I'm very mindful that this is taxpayer money and I'm mindful that taxpayers are happy to help their fellow Australians in trouble," he said.
"But they do expect government agencies to be as careful as they can separating the legitimate from the illegitimate."
Mr Shorten said he was concerned there had been, or could still be, opportunistic behaviour that was "robbing" from flood victims.
"I'm asking Services Australia: 'Are we catching everyone?'" he said.
"I want to make sure that our detection systems for fraud are what they should be, and anything other than that undermines public confidence in the provision of support for victims."
He said there were now 793 criminal investigations underway.
More than $1 billion has been handed out to Australians this year in flood support.
