On Sunday, the Turnbull government announced it would permanently ban asylum seekers who attempt to reach Australia by boat from ever entering the country, even if they are genuine refugees and seek to come as tourists or on business decades later.

Legislation will be introduced to Parliament in November, applying to all adults detained on Manus and Nauru and backdated to July 2013.

Mr Dutton said refugee and asylum-seeker advocates should stop advising detainees to refuse to move to third countries because the government would eventually cave in and bring them to Australia.

"What we don't want is if someone is to go to a third country, that they apply for a tourist visa or some other way to circumvent what the government's policy intent is by coming back to Australia from that third country," Mr Dutton told ABC radio on Monday.

"We are not going to allow people smugglers to get back into business."

"There are a lot of people who believe, regardless of what we say, that they will eventually come to Australia and there are many advocates who are messaging that each day to people on Manus and on Nauru."

There is growing speculation the government is preparing a new third country deal to resettle detainees on Manus Island and Nauru. While Mr Dutton restated the government's opposition to a previous deal negotiated between the Gillard government and New Zealand, he wouldn't be drawn about possible fresh negotiations with New Zealand and even the United States.

The laws announced Sunday would prevent a refugee who was on Manus Island or Nauru and subsequently resettled in a country like New Zealand from being able to fly to Australia, where they could attempt to stay.

Unaccompanied children and those who were brought on boats by their parents would be exempt from the laws and some ministerial discretion would apply, Mr Dutton said. He also said the laws would not hit any legal hurdles.

"The legal advice is very clear from the international division of the Attorney-General's department, it's very clear from the Australian Government Solicitor. There are no constitutional issues here... and we are absolutely confident in terms of the constitutionality and that we meet our international obligations."

Labor and crossbench senators are already coming under pressure from the Greens to reject the government's plan.

Greens leader Richard Di Natale said on Monday the government was chasing a "mean, cruel agenda of One Nation".

"I'm hopeful that if Labor shows a little bit of courage on this issue ... there's a real chance we'll be able to strike this legislation down," he said.