Australia's Home Affairs Department has admitted it didn't seek any advice before revoking the citizenship of an Australian ISIS recruiter it claims is also Fijian.
The Fiji government has maintained that 27-year-old Neil Prakash, who is jailed in Turkey, never held or sought Fijian citizenship.
If true, it would mean Australia broke international laws by rendering Mr Prakash stateless.
Australian Immigration Minister Peter Dutton said earlier this month that legal advice showed Mr Prakash was a Fijian citizen.
But Australian media report Home Affairs Department official Linda Geddes saying no legal or expert advice was sought.
Ms Geddes told a committee hearing on Wednesday that no attempt was made to verify Mr Prakash's citizenship with Fiji.