Police in Papua New Guinea have threatened to arrest all managers at the Manus Island detention centre if three Australian men accused of attempted rape are not flown back to PNG.

The three men and a Papua New Guinean woman were reportedly found naked, intoxicated and sniffing an unidentified substance in mid-July.

Provincial police commander Alex N'Drasal said the woman involved was interviewed on Wednesday and alleged the men tried to rape her.

The woman reportedly told police she was given pills and sexually assaulted.

Police say they are investigating reports of "attempted rape, indecent exposure and sexual assault".

Commander N'Drasal has demanded Australia's Department of Immigration and Border Protection (DIBP) arrange the return of the three expatriates by close of business Thursday.

"If they are not here, we will proceed on to arrest all those managers who facilitated the deportation of those three Australians, because their actions prevented the course of justice," he told the ABC.

The woman involved is understood to also work at the Australian-funded detention centre and PNG police said she could identify the men sent home.

The Immigration Department said in a statement that it had known about the incident for two weeks and said the men in question were employees of the centre's security provider Wilson Security.

"The Department of Immigration and Border Protection categorically rejects assertions made over recent days that it was involved in a 'cover up' of an alleged sexual assault on Manus Island," the statement said.

"To clarify the matter, the Department was made aware immediately in mid-July of an incident involving three service provider staff and a locally engaged staff member. There were no allegations of a criminal nature made as a result of this incident. However, the alleged incident was inconsistent with expected behaviours and contrary to the service provider's code of conduct.

"The three service provider staff were stood down and returned to Australia as part of standard procedures with the full knowledge and concurrence of the PNG police."

But PNG police insist they did not agree to send the men home and remain furious at the actions of Australian officials.

"They [DIBP] are concealing a lot of information from us and that's a total lie," Commander N'Drasal said.

PNG's prime minister Peter O'Neill has called for an investigation into the matter.

"After I receive the report from our officials, I will take this matter up with the Australian Government and we will come to the bottom of this," Mr O'Neill told local television station EMTV.

"I agree with the Commissioner, he is in charge of this, he must investigate who sent this particular person out of the country without him facing the law."

On Tuesday, former prime minister and one of the founding leaders of independent PNG, Sir Michael Somare, said PNG should not have agreed to host the Australian-run immigration detention centre on Manus Island.