Three people who obtained Australian citizenship through disgraced former NSW Liberal MP Daryl Maguire could have their status revoked.
A Senate estimates hearing in Canberra on Friday was told of the 14 cases of alleged visa fraud linked to Mr Maguire, nine people were now onshore with visas in Australia and three of them had gone on to secure citizenship.
"That is extraordinary - how did we get to a point where three people got to become citizens of the country when it appears according to Mr Maguire he fraudulently got them into Australia?" Labor senator Kristina Keneally asked.
"What kind of border control is this?"
Home Affairs department secretary Michael Pezzullo said it was the subject of both an administrative inquiry and a criminal investigation.
However, he was firm as to the potential consequences of any proven wrongdoing.
"If visas have been granted in relation to false credentials or matters fraudulently otherwise, those visas will be cancelled as a general principle," he said.
"Even in the case where citizenship has been gained, the act allows for the stripping of citizenship and we will come down in a very tough-minded way once we've done our processes."
Mr Pezzullo said if the processes discovered fraud "the advice to the minister will be take it off them".
Senator Keneally said it was extraordinary, noting Mr Maguire's former relationship with NSW Premier Gladys Berejiklian.
Mr Pezzullo said the relationship and Mr Maguire's political party was irrelevant to his inquiries.
"Irrespective of (Mr Maguire's) party, I don't care what party he is in, I don't care what personal relationship he's been in ... we will follow the law and if it is appropriate we will sanction the kind of behaviour you are describing."
Australian Border Force Commissioner Michael Outram said his agency's investigation had begun on October 8.
If any criminal offences were uncovered they would be referred to the Australian Federal Police, he said.
The cash-for-visas scheme dates to 2013 and has come to light during an ongoing NSW corruption inquiry.
Mr Maguire is accused of abusing his public office while serving as a state MP.
He once received thousands of dollars in cash to his taxpayer-funded office, with the money linked to securing Australian visas for Chinese nationals.
Mr Maguire has admitted making representations to immigration officials as well as federal politicians.
Australian Associated Press