About 600 men at the centre on Manus Island do not want to leave, saying they fear being attacked outside.
Meanwhile, New Zealand has reiterated its offer to accept up to 150 refugees from Australia's detention centres.
Canberra has repeatedly rejected New Zealand's offer.
Australia holds asylum seekers who arrive by boat on PNG's Manus Island, and on the Pacific island of Nauru.
Australia withdrew from the Manus Island centre on Tuesday, following a PNG court ruling that the centre was unconstitutional.
