Former Labor immigration minister Chris Bowen said the Manus Island detention centre was not appropriate for children but was advised by intelligence agencies, including ASIO to publicise a "blanket exemption" when he re-installed the controversial offshore detention centre.

Mr Bowen told the Australian Human Rights Commission inquiry into children in detention that he supported offshore processing as a deterrent to people smugglers, saying exempting children from the hardline policy would have encouraged people smugglers.

"Any particular groups of people would provide a significant incentive to people smugglers to load boats with that class of people, whether it be children [or] women," he said at the final hearing in Sydney on Tuesday.

"That was advice given to the government by various agencies."