The Australian government has unveiled plans to give lifetime bans to any asylum seekers who attempt to reach the country by boat.

The ban on visas would apply to people travelling as tourists, for business, or who married an Australian.

The proposal will be put to parliament this week, and Prime Minister Malcolm Turnbull said it would send the "strongest possible signal" to people-smugglers.

At the moment, Australia takes asylum seekers who arrive by boat to off-shore processing centres in Nauru and Manus Island in Papua New Guinea.

Even if they are found to be genuine refugees, they cannot be resettled in Australia - they can either return home, resettle in Manus or Nauru, or go to a different country.

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

"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."

The opposition says it is yet to decide whether to back or oppose the new law.