Senior officials from the Department of Home Affairs have admitted nine of the 14 named recipients of the scheme remain onshore with three now Australian citizens.

The former NSW MP was accused of using his role in public office for personal gain and admitted to running the visa scheme during an ICAC hearing in October. It was revealed he allegedly received thousands of dollars in exchange for supporting visa applications lodged under false pretenses.

Home Affairs deputy secretary Andrew Kefford told a parliamentary committee on Friday afternoon it was still conducting its own investigation into the matter despite Mr Maguire's admission.

"We still have to go through the administrative processes of determining and there is, you know, under the Act, the ability to cancel visas where fraud is proven," Mr Kefford said.

Home Affairs secretary Michael Pezzullo said if the department's investigations revealed the visas were fraudulently received, then they, and any citizenship since received, could be stripped.

"If visas are being granted in relation to false credentials or matters fraudulently otherwise, those visas will be cancelled as a general principle," Mr Pezzullo said.

"The Act allows for ... the stripping of citizenship and we will come down in a very tough-minded way once we've done our process."

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Labor Senator Kristina Keneally said she thought it was extraordinary the process never raised a red flag throughout its seven-year course.

"We've managed to go from [the visa recipients] arriving ... apparently fraudulently on a visa all the way through to citizenship over a course of seven years," Senator Keneally said.

"If it hadn't been for the ICAC investigation, which by the way I think proves the necessity of anti-corruption bodies, none of this may have ever come to light."