A man sleeping at the former Manus Island detention centre. Supplied: Asylum Seeker Resource Centre

The mysterious departure of the Department of Home Affairs’ top doctor has sealed a rare opening used by external doctors and advocates to lobby for the interests of sick refugees and asylum seekers.

Dr John Brayley served as the inaugural surgeon general and chief medical officer of the Australian Border Force for two years before he quietly departed the dual role in September 2017. More than four months later, a spokesperson for the department confirmed that the process to fill the positions is ongoing.