A retired lawyer has asked Australia's peak workplace, health and safety authority to "please prosecute" the Immigration Department for allegedly breaching its duty of care in detention centres.

Former WorkSafe Victoria prosecutor Max Costello said last week that although Comcare has regularly inspected immigration detention centres in Australia and regional processing centres on Nauru and Manus islands, the agency has yet to act on reports of "death, abuse, and illness" impacting workers, detainees, and transferees.

Mr Costello wrote twice to Comcare last year calling for action but "thought 12 months was more than reasonable" to wait before going public.

He said the recent release of incident reports from Nauru and two senate inquiries into offshore processing showed risks of sexual, physical and psychological harm had been identified but neither eliminated nor minimised.

Mr Costello has asked Comcare to include onshore detention centres in its case because "prolonged detention itself eventually gets to people and damages their mental health ... those people need to be removed as soon as possible".

"Mr Dutton and other spokespersons of the Government including the Prime Minister keep asserting that the health and safety of asylum seekers at Nauru and Manus is the responsibility of the Nauruan and [Papua New Guinean] governments respectively and that's just legally not true," he said.

He said the Australian Work Health and Safety Act 2011 "is quite clear" that a "health and safety duty cannot be transferred to another" person, contractor or government and that any such transfer would be legally void.

A spokesman for Comcare said investigations were continuing.

Immigration Minister Peter Dutton has been contacted for comment.