The Australian and PNG governments announced on Wednesday that their offshore detention arrangements would end in December.

Future asylum seeker boat arrivals will be sent to Nauru as the sole Australian regional processing centre and PNG will “assume full management of regional processing services … and full responsibility for those who remain”.

There are still 124 men in PNG, down from a peak of more than 1,500, with dozens held in Port Moresby recognised as refugees under the UN Refugee Convention.

Refugee advocates accused Australia of abandoning the detainees who remain in PNG.

The AHRC says it holds "serious concerns" the upcoming move will see Australia in breach of its human rights obligations.

It said that, under the UN Refugee Convention, “obligations remain even if Australia transfers people to a third country for their claims to be processed”.

The AHRC also holds concerns about people being returned to countries against their will, arbitrary detention, a lack of “robust independent monitoring mechanisms”, the health and safety of people in detention, and living conditions in PNG.

The commission said Australia should process all asylum seekers in Australia.

The United Nations High Commissioner for Refugees has also voiced concern over the move.

“Australia’s withdrawal from its offshore arrangements in PNG ought to be welcome news.

“Sadly, it is happening without confirmed viable long-term solutions for many of the individual refugees and asylum seekers it will affect,” the UNHCR said in a statement.

The agency said it has long “advocated against policies under which states externalise asylum and protection obligations” and highlighted “grave risks to the global refugee protection regime when countries seek to shift their responsibilities onto others, typically developing nations where refugee protection standards are poor”.

The UNHCR also expressed concern over a new memorandum of understanding signed last month between Australia and Nauru to extend offshore processing there indefinitely, saying it is “not a long-term solution”.

Asked by SBS News about whether Australia should maintain responsibility for the detainees and whether the move is in keeping with human rights and international refugee treaty obligations, the Department of Home Affairs said: “Regional processing arrangements in PNG and the management of individuals under those arrangements has always been the responsibility of the PNG government – this has not changed”.

A number of Australian federal court and coronial inquests into offshore processing deaths on Manus Island have in judgments and findings stated the “duty of care” for asylum seekers remains with the federal government.

PNG has for years been trying to extract itself from involvement with Australia’s offshore processing, which is seen as a stain on the country’s international reputation.