UPDATED: 9.11AM Australia's Labor opposition's jumping on a decision by the Papua New Guinea Supreme Court.

It's ruled Australia's detention of asylum seekers on Manus Island is illegal, and says steps to end detention must be taken immediately.

LISTEN ABOVE: Julian Burnside QC speaks to Jack Tame on the Mike Hosking Breakfast

The court has ruled the 850 men detained on the island are having their rights to personal liberty breached.

Civil liberties lawyer Julian Burnside QC told Jack Tame it's hard to tell exactly what the Australian government will do.

"I wouldn't be surprised if the Australian Government, with it's complete lack of respect for human decency, tries to work out a way around the verdict."

Mr Burnside QC said it's likely Australia will try to find a way around the decision.

"For example, they might say that the detention centre is closed and that they are free to move in and out of the detention centre. I don't think that would prevent it from being detention, because they are still stuck on Manus Island."

Mr Burnside said the detainees could possibly be moved to Nauru or Christmas Island.

Correspondent Steve Price told Jack Tame the verdict doesn't mean they asylum seekers will be going anywhere.

"You can have the people there but you can't actually keep them in a prison, and so like Nauru which is now an open detention centre, the Government says that's what they will do."

Australia correspondent Donna Demaio told Rachel Smalley Labour's immigration spokesperson Richard Marles said the ruling is of concern.

He wants to see the Immigration Minister, Peter Dutton sent to Papua New Guinea to hold urgent talks and find out what's going to happen.

Ms Demaio said so far there's only been a brief response by Mr Dutton.

"He's already said that the men in detention will not be relocated to Australia. He said no one who attempt to travel illegally to Australia by boat will settle here."

Mr Dutton has suggested those in detention should be able to resettle in Papua New Guinea.