SYDNEY (Reuters) - Australia will not be allowed to walk away from legal, financial and moral responsibility for nearly 800 men when it closes its asylum seeker detention center in Papua New Guinea (PNG) on Tuesday, PNG's immigration minister said.

Human rights advocates are warning of a looming humanitarian crisis when the Manus Island center closes if the men are not properly resettled, with hundreds of the detainees refusing to leave the center for fear of being targeted by locals.

PNG Immigration Minister Petrus Thomas said late on Sunday that Australia will remain responsible for the welfare of the men that have been detained in the Australian-funded center for more than four years.

Australia refuses to allow asylum seekers arriving by boat to reach its shores, detaining them in camps in PNG and Nauru in the South Pacific. The United Nations and rights groups have for years cited human rights abuses among detainees in the centers.

"It is PNG's position that as long as there is one individual from this arrangement that remains in PNG, Australia will continue to provide financial and other support to PNG to manage the persons transferred under the arrangement until the last person leaves or is independently resettled in PNG," Thomas said in an emailed statement.

Australia has already said it would spend up to A$250 million ($195 million) housing the nearly 800 refugees and asylum seekers in Papua New Guinea for the next 12 months after its controversial detention center closes.

The Manus center is scheduled to close on Tuesday, after being declared illegal by a PNG court, with 600 men set to be moved to three new transit camps. Just under 200 men have already relocated.

Despite threats that basic services like electricity and water will be cut off, the remaining detainees are refusing to move, citing fears for their safety. Fears of violence have been stoked further after PNG sent extra security forces to the camp.

The relocation of the men is designed as a temporary measure, allowing the United States time to complete vetting of refugees as part of a refugee swap deal.

The United States has agreed to take up to possibly 1,250 refugees from Australia's two Pacific detention centers, but so far only 25 men from Manus have been resettled. In exchange, Australia said it will resettle Central American refugees.

Australia has said those detainees not resettled in the United States will be allowed to stay in PNG or the tiny Pacific island of Nauru. But nearly all have refused invitations to settle permanently in both locations.

Thomas said PNG will not force anyone to remain.

"It is the responsibility of Australia to pursue third country options," he said.

Australia's acting Prime Minister Julie Bishop said on Monday that Canberra was exploring possible deals for resettlement, but added "those who have found not to be refugees should go home".

"They've been found by the (United Nations) not to be owed protection so they should return to their homes," she said.

The bulk of the detainees come from war-torn countries such as Syria and Afghanistan, and Pakistan, Iran, Sri Lanka and Myanmar.

(Reporting by Colin Packham and Jane Wardell in Sydney; Editing by Michael Perry)