More than 600 asylum seekers and refugees are refusing to leave the Manus Island immigration detention centre ahead of its closure next week.
Authorities are planning to axe food services, access to drinking water, medical treatment, education programs, electricity and sewerage from Tuesday week.
Alternative accommodation and services will be provided to refugees while they wait for resettlement in a third country.
There are also 156 people whose bid for asylum has been rejected.
A Senate committee on Monday heard that 606 people still at the centre, and required to leave by the closure deadline, were refusing to move out.
It's unclear what the status of these asylum seekers and refugees are in the detention process.
Asked if they would be removed by force, Immigration Department secretary Michael Pezzullo said that was a matter for the Papua New Guinean government.
Mr Pezzullo suggested the ordinary laws of trespass may apply because PNG was planning to reoccupy the former military facility.
"They don't have a human right to trespass on a naval base," he told senators.
Greens senator Nick McKim said the Australian government was risking a human rights disaster and loss of life by not making any security arrangements for people who chose to stay at the centre.
Senator McKim pointed out PNG navy personnel had previously fired shots at the centre and some refugees had been attacked with machetes in nearby Lorengau.
Mr Pezzullo rejected claims people were too scared to leave the centre, saying refugees now come and go as they please.
Counsellors, psychologists and psychiatrists will continue to be available to refugees at the East Lorengau transit centre.
All service providers and Australian personnel will leave by the closure date.
The cost of transition arrangements for Australia has been estimated at between $150 million and $250 million for the next 12 months.
Meanwhile, the department has revealed two refugees and an ineligible asylum seeker on Manus Island have taken up the offer to transfer to Nauru.
The hearing was told the Nauru government had shown interest for a long time in taking more refugees from Manus.
Labor senator Kim Carr pointed out Nauru charges about $10,000 for a refugee visa.
The department officials admitted refugees in Australia for medical treatment were precluded from applying for resettlement in the US.
The hearing was told 40 people in that situation had expressed an interest in going to the US.
The US has agreed to resettle up to 1250 people and so far about 50 have travelled to America.
