Three Australian guards on Manus Island found naked with a woman who claims she was drugged and raped were sent home before local authorities could investigate, the ABC reports.

PNG police said the men and the local woman were found in a state of undress, drunk and sniffing an unidentified substance in mid-July.

But Australia's Department of Immigration and Border Protection has angered PNG police by allowing the detention centre guards to return to Australia before an investigation could be carried out.

PNG's highest ranking policeman Gari Baki said the incident was indicative of the lack of oversight local authorities had over the detention centre

The woman, believed to be a contractor at the immigration detention centre, claims she was drugged and raped, said local MP Ronny Knight who has spoken to her family.