Attorney-General George Brandis says the appointment of an Indigenous royal co-commissioner into youth justice in the Northern Territory was being considered by the Prime Minister last week.

Former NT chief justice Brian Martin stood down as royal commissioner yesterday, four days after his appointment was announced by Malcolm Turnbull following the Four Corners report on the treatment of child prisoners in the Don Dale detention centre in Darwin.

High-profile Indigenous leader Mick Gooda and former Queensland Supreme Court judge Margaret White were named as his replacements, following increasing community and political pressure to appoint an Indigenous representative.

Senator Brandis this morning defended the appointment of Mr Martin, but said he and Mr Turnbull had already been exploring the potential for an Indigenous representative.

"Before Mr Martin changed his mind and decided that he was not prepared to continue, the Prime Minister and I had already had discussions between ourselves about the desirability of adding an additional Indigenous royal commissioner," he said.

"We never decided against it."

Senator Brandis' comments follow those made by his colleague, Special Minister of State Scott Ryan, who told Sky News on Sunday the Coalition had ruled out appointing Indigenous co-commissioners.

Senator Brandis also defended the appointment of Mr Gooda, who has been questioned over a tweet he posted last week calling for the NT Government to be sacked.

The Attorney-General said he was not concerned over any conflict of interest.

"You will not find an Indigenous leader in this country who hasn't had some sharp and strong things to say about the way in which the system treats Indigenous youth," he said.

"If you found somebody, an Indigenous leader who hadn't expressed concern about this over the years, then they wouldn't be worth their salt as a leader."

Mr Gooda walked back from his remarks when questioned on the matter yesterday, citing an emotional response.

"Tuesday, you know, was a day of emotions and people had all sorts of emotional responses," he said.

"In the clear light of day, I probably wouldn't think that."

Opposition Leader Bill Shorten also defended the comments, saying "there are a lot tougher things being said about the Giles Government than what Mr Gooda said".