Immigration Minister Scott Morrison has ordered that no asylum seekers be sent to Manus Island, instead funnelling them to the small Pacific Island of Nauru.

In changes made to the Migration Act on July 15, Mr Morrison revoked the direction to send male asylum seekers to Papua New Guinea's offshore processing centre on Manus Island.

Manus Island detention centre

In the changes made under subsection 198ad(5) of the Migration Act 1958 ('the act'), obtained by Fairfax Media, Mr Morrison writes it is in the "public interest" to "direct officers to take unauthorised maritime arrivals to the Republic of Nauru."

It says the only people who are exempt from the Act are asylum seekers who are flown to Australia for medical reasons. "In this instance I direct officers to take the unauthorised maritime arrival to Papua New Guinea when the person no longer needs to be in Australia for the medical treatment," the statement says.