Immigration minister Brendan O'Connor has admitted that his comments regarding the number of people scamming the 457 immigration visas scheme is not based on official facts and figures.
Last week, the politician said during a television interview that 10,000 people were rorting the system, although his department were unable to confirm where he had come up with the statistic.
Mr O'Connor now says the number was his own "estimate", but stood by his opinion that there are "more than a few transgressions".
''Well, I'm making a forecast. I'm making a forecast like others have made forecasts. The difference is I seem to be being challenged - fine," he told ABC's AM program on Friday (May 3).
''We don't have an exact, precise figure. That's not possible under the current arrangements, but it is significant and I make no apology [for] fixing a scheme that has problems."
Mr O'Connor's remarks were slammed by the Opposition and several industry groups, with Australian Chamber of Commerce and Industry chief executive Paul Anderson telling The West Australian the number had been "plucked from the air".
Scott Barklamb, Australian Mines and Metals Association industry executive director, had similar criticisms, also accusing the minister of announcing a statistic that was "plucked out of thin air over the weekend".
The immigration minister's comments followed the release of Department of Immigration and Citizenship data revealing a 19.2 per cent increase in the number of 457 visa holders in Australia as of March 31 2013, when compared with the same date the previous year.
He expressed particular concern for a rise in skilled visas granted for people in the lowest-paid jobs, such as accommodation and food services, and retail, with these industries seeing growth of 99 per cent and 75 per cent respectively.
In his recent ABC interview, Mr O'Connor said he estimated the 10,000 rorters figure after looking at "the fall in nominal and real wages in certain occupations and certain sectors" and by looking at the "fact that there is a massive widening gap between the total employment growth rate in certain segments".
The politician also pointed to anecdotal evidence of jobs being "dressed up", and not fulfilling the specifications usually associated to those roles.
Despite this, various industry commentators have rejected the Gillard government's claims, including chief executive of the Australian Industry Group Innes Willox, who said there is little evidence to show 457s are being systematically abused.