One asylum seeker is dead and two others have been flown to Australian hospitals after more rioting at the Manus Island detention centre.
In the second consecutive night of unrest at the Australian-run centre in Papua New Guinea, 77 people were injured during a three-hour riot.
There are conflicting reports over whether PNG police entered the facility on Lombrum Naval Base, just a few kilometres from the provincial capital Lorengau.
Immigration Minister Scott Morrison would not be drawn on what sparked Monday night's riot and said Australian authorities were unaware of the exact circumstances of the death since it happened outside the facility where security was the domain of PNG police.
PNG launches investigation
PNG authorities will investigate the death and a shooting that injured one of the other asylum seekers.
"This is a tragedy but this was a very dangerous situation where people decide to protest in a very violent way and to take themselves outside the centre and place themselves at great risk," Mr Morrison told reporters in Darwin on Tuesday.
"If you behave in an unruly way and in a disorderly way then you subject yourself to the response of law enforcement."
Detention security provider G4S said asylum seekers broke through the perimeter fence after protesting for two days.
"Claims that the transferees breached the fence following internal attacks on them by local residents are unfounded," G4S said in a statement.
"A number of transferees were injured after they breached the perimeter fence and the matter became a law enforcement issue for PNG authorities."
Call for closure of detention centre
Australian Greens leader Christine Milne is demanding the detention centre be immediately closed following the death.
"This is exactly what has been threatened in what has become Australia's gulag," she told reporters in Hobart.
Mr Morrison had to provide a full explanation, she said.
"Ministerial responsibility has to mean something and Scott Morrison has to stop hiding.
"It is craven and cowardly for him to constantly refuse to answer questions when it suits him and now try and pass this off as something that the PNG authorities will have to deal with.
"He has to deal with it, he's the minister, he's been bragging about the conditions in these detention centres."
PNG prime minister Peter O'Neill has dispatched the nation's chief migration officer, Mataio Rabura, to the island province to investigate.
Describing the asylum seeker's death as a tragedy, Mr Morrison said the government had taken steps in recent weeks to increase security at the facility, having learned from similar violent incidents at detention sites on Nauru.
"On this occasion, the centre has not been destroyed, the centre will be able to resume operations," he said.
Dozens injured in the violence
Of the 77 injured in the latest riot, 40 have been discharged from hospital.
Twenty-two had minor injuries and 13 had serious injuries.
One person was evacuated to Australia for treatment for a skull fracture and another, who was shot in the buttocks, was also due to be flown to Australia for treatment.
Local PNG MP Ron Knight said responsibility lay solely with G4S.
"This shows that shoddy camp management and lack of responsible authority is prevalent at Lombrum," he told AAP.
Mr Knight said his staff were turned away from the centre when they tried to find out what was going on.
"Yes, all guards that turned back my staff are expatriate G4S staff," he said.
"They are arrogant and totally responsible for the situation."
G4S said its staff restored order without using force.