Australia has moved to bar any refugee or asylum-seeker who arrives in the country illegally by boat from ever being able to apply for a visa, even as tourists or for business.

The lifetime ban will be put to parliament when it next sits, with Prime Minister Malcolm Turnbull saying it was necessary to send an "absolutely, unflinching, unequivocal message" that boatpeople will never be allowed in Australia.

"This is a battle of will between the Australian people, represented by its government, and the criminal gangs of people-smugglers," he said.

"You should not underestimate the scale of the threat. These people-smugglers are the worst criminals imaginable. They have a multibillion-dollar business.

"We have to be very determined to say no to their criminal plans."

In pictures: Life on board a refugee rescue ship Show all 10 1 /10 In pictures: Life on board a refugee rescue ship In pictures: Life on board a refugee rescue ship Refugees sleep on the deck of MV Aquarius Alva White/MSF In pictures: Life on board a refugee rescue ship An overcrowded rubber vote before a rescue by the MV Aquarius Alva White/MSF In pictures: Life on board a refugee rescue ship Young boy being rescued from a rubber boat by the MV Aquarius Isabelle Serro/SOS Mediterranee In pictures: Life on board a refugee rescue ship The rescue of a wooden boat with more than 400 peopl on board by the MV Aquarius on 21 August Isabelle Serro/SOS Mediterranee In pictures: Life on board a refugee rescue ship Women rescued on MV Aquarius approaching Italy in the early morning Alva White/MSF In pictures: Life on board a refugee rescue ship Crew on the MV Aquarius search for a missing boat Alva White/MSF In pictures: Life on board a refugee rescue ship Rescue on the 21st August of a wooden boat carrying more than 400 people and a rubber boat with 120 people crammed on board. Ferry Schippers/MSF In pictures: Life on board a refugee rescue ship The night rescue of 124 people after they had been on the water for 20 hours by the MV Aquarius Peter Eickmeyer/SOS Mediterranee In pictures: Life on board a refugee rescue ship The MV Aquarius rescue vessel operated by Doctors Without Borders (MSF) and SOS Méditerranée in the Mediterranean Sea Alva White/MSF In pictures: Life on board a refugee rescue ship Jacob Goldberg, MSF's team leader on board the MV Aquarius rescue ship Alva White/MSF

Amendments to the migration act would be backdated to mid-2013, when former Labour prime minister Kevin Rudd declared: "As of today, asylum-seekers who come here by boat without a visa will never be settled in Australia."

Canberra currently sends all boatpeople to offshore processing camps on the Pacific islands of Nauru and Papua New Guinea's Manus.

They are already blocked from being resettled in Australia even if found to be genuine refugees. They can either return home, make a life on Manus or Nauru, or go to a third country.

The new legislation would affect those sent to Nauru and Manus from July 19, 2013, including those who have returned home, and anyone who arrives in the future.

But children will be exempt and the immigration minister would have the power to make exceptions.

The Nauru facility holds just over 400 men, women and children.

Some 800 men are detained on Manus, which Australia in August agreed to close after a Papua New Guinea court ruling that holding people there was unconstitutional and illegal.

Rights group have alleged there is widespread abuse and self-harm in the camps.

Mr Turnbull said the move would reinforce to refugee advocates still hoping Australia will accept some of those on Nauru or Manus that it will never happen.

"We have one of the most generous humanitarian programmes in the world," he said.

"But the only reason we can do it, the only reason it has the public acceptance that it does, is because we are in command of our borders."

Australia has boosted its annual humanitarian refugee intake in recent years from 13,750 to 18,750, and has also agreed to take 12,000 people displaced in Syria and Iraq.

Refugee advocates said the plan was unacceptable, with Save the Children fearing it will further exacerbate the mental anguish of those held in the Pacific camps.

"We have grave concerns that this kind of announcement will push people over the edge," said the organisation's director of policy and public advocacy in Australia Mat Tinkler.

"The government must act urgently to give hope to these people, not continue to take it away."

Refugee and Immigration Legal Centre lawyer David Manne agreed that the proposal punished genuine refugees.

"This does nothing to address that fundamental question about where they are going to be taken so that they can rebuild their lives in safety and with dignity," he told the Australian Broadcasting Corporation.

Since the start of "Operation Sovereign Borders" in September 2013, the conservative government has managed to halt the flood of boat arrivals, and drownings, that characterised previous Labour administrations.