Papua New Guinea's Prime Minister has clarified comments he made at Australia's National Press Club (NPC) that he wants the Manus Island regional processing centre to eventually close.

Key points: Peter O'Neill said the Manus Island centre had done a lot of damage to PNG's reputation

Peter O'Neill said the Manus Island centre had done a lot of damage to PNG's reputation PM said it is up to Australia to close the centre in the future

PM said it is up to Australia to close the centre in the future He said there are questions around the cost of resettling refugees

Peter O'Neill told the ABC's Pacific Beat program following his Canberra address that the decision needs to be made by Australia.

"No, I did not say I want the Manus centre closed, I said that it is up to the Australian Government, that it is their call, that is their responsibility. But I stated that we cannot hold the refugees there forever," he said.

"We need to process them, we need to resettle them, we need to move them back to their country of origin if they are not genuine refugees, but we cannot hold them there forever."

Earlier, Mr O'Neill told the NPC the centre should close in the future.

"At some stage, of course, we need to close the centre," he said.

Mr O'Neill said the Australia-funded regional processing centre, currently home to 916 male asylum seekers, had "done a lot more damage for Papua New Guinea than anything else".

He told Pacific Beat the detention centre had harmed the country's reputation.

"Some of our communities have been unfairly displayed as being a lawless society, a society where you cannot live," he said.

"We've been living for thousands of years freely and peacefully. Those kinds of comments do not fare well with our communities in Papua New Guinea."

Mr O'Neill described the centre to the Canberra press gallery as an inherited problem, and said questions remained around the costs of resettling refugees.

"We have issues about the cost of the resettlement, who is going to pay for it," he said.

"Certainly, the (PNG) Government does not have the resources to resettle the refugees as required, but we will play our role."

O'Neill denies issues with law and order at centre

Mr O'Neill was also questioned by the press gallery about the allegations of sexual assault at the centre, which were detailed in Senate estimates last year.

Immigration staff told a Senate committee that from March 24, 2014, to September 29, 2015, the regional processing centre recorded 14 sexual assaults, 213 physical assaults and 798 occurrences of abusive and/or aggressive behaviour.

At the time, none of the 14 cases of sexual assault reported had led to a prosecution.

Mr O'Neill today denied any issues with law and order, saying that people on the island were being "well looked after".

"Arriving there one day and seeing only 10 policemen does not necessarily mean we have a law and order problem," he said.

His address followed reports of a blow-out in both the cost of running the centres and the average detention period of asylum seekers.

Australian Government figures issued earlier this year showed the average number of days spent in immigration detention — both offshore and in Australia — had hit a record 446 days.