Asylum seekers who are murderers and sex offenders could enter Australia through medical treatment transfers, the home affairs minister says.
Murderers and sex offenders could slip into the country if sick refugees are more easily able to seek medical treatment in Australia, Home Affairs Minister Peter Dutton has warned.
But Labor has rubbished his claims as "nonsense" and argued the minister would still be able to refuse entry to anyone who posed an unacceptable risk to Australia.
Mr Dutton is fighting changes to medical evacuations of asylum seekers that he believes will trash the offshore processing system.
Legal changes being driven by Sydney independent MP Kerryn Phelps, known colloquially as the Nauru Bill, are expected to clear federal parliament early next year.
The legislation would allow critically ill refugees to be flown to Australia for medical treatment on the advice of two treating doctors.
The immigration minister would still need to sign off on the transfers.
However, Mr Dutton said he had advice to the contrary.
"The advice to me is clear that the minister doesn't have the ultimate say," he told Sky News on Monday.
"In many circumstances, you could have people with questionable backgrounds, people that have been charged, even people that have been investigated for serious sexual assault matters for example, who could come if they had a medical reason."
Legal advice to the government from ASIO suggests the minister can only reject a medical transfer if an asylum seeker poses a threat linked to terrorism, espionage, foreign interference and politically-motivated violence.
Murder, sexual assault, child abuse, physical violence and domestic violence would not be within the minister's scope to block a transfer.
However, Labor says these criminals would be covered by a section of the ASIO Act which allows the minister to refuse entry to anybody who poses a serious threat to Australia's territorial and border integrity.
Opposition Leader Bill Shorten questioned whether the government would prefer sick and dying people were left untreated on Manus Island and Nauru.
"I don't want people to be left on Nauru to die just because the government doesn't want to treat them in Australia and then send them back to Nauru," he told reporters in Whyalla.
Under the legal changes, the minister would be given just 24 hours to make a determination on medical transfers, and there would be greater transparency over decisions to deny transfers.
Ahead of Labor's national conference in Adelaide next week, a group of refugee advocates within the party are calling for an end to offshore processing and boat turnbacks.
However, Mr Shorten said Labor remained fully committed to both border protection measures.
"I am confident the party understands the position I've outlined and that is the policy I will be taking to the next election," he said.
Meanwhile, human rights lawyers have launched two class actions on behalf of asylum seekers on Nauru and Manus Island.
The lawyers allege the 1200 people have been subjected to torture, crimes against humanity and intentional harm by the Australian government.