Papua New Guinea Immigration Minister Petrus Thomas said authorities would take steps on Monday (local time) to forcibly remove around 450 men who remain in an abandoned Australian detention centre without food or running water.
Hundreds of men have barricaded themselves into the Manus Island centre for more than 13 days without regular food or water supplies, defying attempts by Australia and Papua New Guinea to close the facility.
"We will be taking steps with relevant authorities to move the residents based on serious exposure to health risk for the food of everyone that is remaining," Thomas said in a statement issued late on Sunday.
The timetable stokes fears of a potential clash between authorities and asylum seekers - drawn largely from Afghanistan, Iran, Myanmar, Pakistan, Sri Lanka and Syria - who have refused to move to three transit centres. The United Nations has warned of a "looming humanitarian crisis."
The standoff has cast Australia's immigration policies into the international spotlight, triggering a rare rebuke from New Zealand, Canberra's closest international ally.
Australia has used the centre, and a camp on the tiny Pacific island of Nauru, to detain asylum seekers who try to reach its shores by boat. It says boat arrivals will never enter Australia, even if found to be refugees, as that would encourage people smugglers in Asia.
The asylum seekers on Manus fear reprisals if they move to the transit centres, pending possible resettlement in the United States. The main camp was closed on October 31 and water and power have been cut off.
Australia and Papua New Guinea both insist the transit centres are safe, offering the asylum seekers the same level of care they had received before the closure of the Manus Island camp.
Papua New Guinea last week removed the fences of the camp, while authorities also dismantled rainwater collection bins and makeshift shelters built to ward off the tropical sun and rain, intensifying pressure on the detainees.
New Zealand Prime Minister Jacinda Ardern said she would seek a meeting on the sidelines of the APEC Summit in Vietnam with her Australian counterpart, Malcolm Turnbull, to discuss the situation.
"No matter what label you put on it, there is absolute need and there is harm being done," Arden told reporters.
Turnbull earlier this month rejected an offer from New Zealand to resettle 150 asylum seekers as it prioritised an existing refugee swap deal he negotiated with former US President Barack Obama last year.
Under that deal, up to 1250 asylum seekers could be sent to the United States and Australia will in turn accept refugees from Central America.
