The federal government is concerned that asylum seekers who leave Manus Island or Nauru for medical treatment may never go back, due to a legal loophole.
Attorney-General Christian Porter has blamed poor drafting of medical evacuation laws passed last week against the government's will for the loophole.
However, Labor's immigration spokesman Shayne Neumann said the new laws had not changed the returns system and if a person is transferred to Australia for temporary medical treatment, they will be returned to Manus or Nauru once doctors advise they have completed medical treatment.