Evidence is emerging that Australia has fired up an old law to begin a fresh mop-up of people it doesn't want, including scores of New Zealanders.

Photo: RNZ

Brisbane immigration lawyer Jennifer Samuta witnessed the impact of the law, called section 116, on people's visas at the Arthur Gorrie remand centre.

"I went in and we had a group of 40 men and the vast majority of [their visas] had been cancelled under section 116," she told RNZ.

The vast majority of the men were New Zealand citizens, many of whom were Samoan, and in the last two months the law appeared to have superseded other powers to trigger immigration detention, she said.

She labelled the law "fast and furious" because people get just five days to respond when notified their visa is about to be cancelled.

It was possible the vigorous activation of the law in the last few weeks marked the federal government moving into a fresh, second phase of detentions and deportations, Associate immigration professor Peter Billings of Queensland University said.

"It may well be that the Minister is now placing reliance on this alternative, broadly formulated power to effect the removal of certain non-citizens."

It would throw the net wider, beyond the criminals and bikies swept up by the until-now most widely-used detention and deportation law called section 501, Mr Billings said.

Under section 501 since 2015, there has been a 10-fold rise in visa cancellations - which triggers mandatory detention - with 55 percent of them New Zealanders.

Section 116 had in recent weeks been used a lot more to cancel refugees' visas, Mr Billings said.

When they were applying for citizenship, they were being questioned, and if there was any discrepancy with what they had previously told officials, this was grounds under section 116 to cancel their visa.

This could happen to any non-citizen, including New Zealanders, given the sweeping powers the law gave the Immigration Minister Peter Dutton and his officials.

"They may cancel a visa if they are satisfied that the presence of that non-citizen may, or would, be a risk to the Australian community.

"That's not a particularly high threshold to overcome on the part of the Minister," Mr Billings said.

The Australian Police Federation is expected to argue at a parliamentary committee on migration next week that the collateral damage from the immigration crackdown, such as on minor offenders and families, was getting out of hand.

The Australian Immigration and Border Protection Department said section 116, "is most often used when a person is deemed to pose an immediate risk".

It said section 501 and section 116 were used most frequently, and it depended on the circumstances used.

It did not provide the numbers of visa cancellations under section 116.

Ms Samuta's law firm SamutaMcComber has put out an online warning, saying "the threshold for visa cancellations in this regard is now much lower and the immediate consequences much more severe".

However, section 116 had a history of being easier to appeal against to get a visa back so was probably not a workable long-term strategy for Mr Dutton, Sydney immigration lawyer Simon Jeans said.

On the other hand, he said, the sped-up five-day response period, and simplified appeal process might have appealed to him.

"There's less of a legal structure ... so they could be looking to push these things through without involving applicants being represented by barristers and solicitors," said Mr Jeans, who for five years until 2015 was a member of the Migration Review Tribunal and the Refugee Tribunal.

Ms Samuta said the bulk of men the law was catching out did have a history of violent offences, but that others were on remand or bail and had not been tried or sentenced yet, or had only minor convictions. She knew of an 18-year-old in this category.

She and the Pasifika and Māori community and lobby groups are now running information sessions about the threat.