Foreign Minister Julie Bishop says contentious changes to visa laws are not aimed at refugees or asylum seekers already in Australia, but has not ruled out that some may be deported.

Key points: Concerns raised that proposed changes could affect people on bridging visas in Australia

Concerns raised that proposed changes could affect people on bridging visas in Australia Ms Bishop says legislation will affect people processed offshore, even if they have been brought to Australia

Ms Bishop says legislation will affect people processed offshore, even if they have been brought to Australia Ms Ley says a small number of people in Australia could be impacted

Concerns have been raised that the proposed changes to the Migration Act could affect people on bridging visas in Australia.

The Coalition wants to ban those sent to Manus Island or Nauru in recent years from ever obtaining any visa for Australia.

The legislation, to be introduced next week, would apply to those who tried to arrive by boat since mid-2013.

Ms Bishop did not rule out the possibility of some people currently in Australia being affected.

She told the ABC that the legislation would only affect the group of people processed offshore, even if they had been brought to Australia afterwards.

"My understanding is that this legislation applies to those in offshore processing centres, including those who may have sought for example medical treatment in Australia, but are part of the cohort whose claim for asylum is being processed in a regional offshore processing centre," she said.

"My understanding is also that claims for asylum that have been processed in Australia, as was done under Labor, are not affected."

Small number of people in Australia could be affected

Her comments follow those made by Coalition frontbencher Sussan Ley, who told the ABC's Q&A program that a "relatively small" number of people in Australia could be impacted.

Coalition frontbencher Sussan Ley spoke of the new ban on Q&A yesterday. ( ABC )

"They would have been processed on either Manus or Nauru or an offshore processing centre, that's what's being targeted by this legislation," she said.

"There would be very few who have been processed on Manus or Nauru and are now in Australia."

The ABC understands that a small number of the approximately 320 people who have been brought to Australia from offshore detention centres in the last three years hold a bridging visa.

The rest are held in detention, which does not require a visa.

Yesterday, Immigration Minister Peter Dutton said the ban would not break Australia's international obligations.

The country's immigration laws will come under the microscope when the United Nations special rapporteur on the human rights of migrants arrives in Australia today.

Turnbull disagrees with Hanson on refugees

Ms Bishop has also dismissed suggestions that the proposed changes are being driven by domestic politics.

One Nation senator Pauline Hanson has taken credit for the policy direction in recent days, but Ms Bishop said that the bill was not designed to appeal to their voters.

Prime Minister Malcolm Turnbull told the ABC he disagreed with Senator Hanson's assertion that refugees were not welcome in Australia.

"We welcome refugees, they have made an enormous contribution to Australia," he said.

"But we are able to do that because we can maintain the integrity and security of our borders ... the Australian Government, elected by the Australian people, determines who comes to Australia."

Opposition Leader Bill Shorten yesterday highlighted One Nation's response to the announcement, telling reporters in Melbourne that the party was "telling" Mr Turnbull what to do.

"I think the Government's got some explaining to do as to its motivations," he said.

"I believe Mr Turnbull is more motivated about keeping One Nation and the right wing of the Liberal Party happy than he is about forming sensible policy."

Mr Shorten has not ruled out supporting the bill.