The United Nations refugee agency has released a scathing report on the Manus Island detention centre in Papua New Guinea.

The report accuses the Australian and PNG governments of breaching their international human rights obligations.

They say the temporary living conditions are harsh and in some cases inadequate.

Representatives of the United Nations High Commissioner for Refugees (UNHCR) spent three days on Manus Island a fortnight ago.

UNHCR's regional representative Richard Towle says they have made a number of recommendations.

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"The key recommendation is to put in place proper processing arrangements as soon as possible and start looking at people's claims," he said.

"The key failing is that there are in place no legal frameworks for the processing of refugee claims.

"If the sole purpose of transfer from Australia to Papua New Guinea was to process people, one would expect there'd be some kind of process in place for people when they get there.

"These 221 people are being held in mandatory closed and indefinite detention, which is a very serious violation of international law."

The UNHCR has long opposed offshore detention. Of specific concern is their view that it is difficult, if not impossible, to meet international standards in remote parts of the Pacific.

Mr Towle says conditions on Manus Island were "harsh, hot humid, damp and cramped".

"If you couple that with the other factors of a closed detention regime and add in the particular vulnerabilities of children, you get a very troubling patchwork of issues that need to be addressed," he said.

He says the current system is damaging children.

"We don't think any further children should be transferred to Manus until these very important planks of policy and arrangements are put in place," he said.

There are 34 children being held on Manus Island and Mr Towle says the Government should consider moving them.

"That's a decision for both governments to review when they've had a look at the totality of the report," he said.

"But certainly our view at this stage is that the current arrangements for children are unsatisfactory.

"Children have been sighted far too close to single males, where there's been disruption and noise and demonstrations."

Both incoming immigration minister Brendan O'Connor and outgoing minister Chris Bowen declined AM's invitation to respond to the report.

In a statement, a spokesman for Mr Bowen said the standards at the regional processing centre are in line with standards for locals on Manus Island.

He also said the processing of asylum claims by the PNG government will occur in due course.