Sydney Roosters coach Trent Robinson spoke briefly on Thursday morning about Mitchell Pearce's "unacceptable" Australia Day behaviour.

Pearce has been stood down from all club duties while the Roosters and the NRL carry out their investigation into the matter.

"After the incident we at the Sydney Roosters have found that Mitchell's behaviour was unacceptable and that's why he's been stood down up until this matter is resolved," Robinson said.

"We have discussed it with players and we're going through discussing it with the NRL. I can't really comment on anything else until it's resolved with the NRL.

"At the Roosters we can't accept that and we won't, but over the next couple of days we'll come to a conclusion with the NRL."

Asked why Pearce shouldn't be sacked, Robinson said any such punishments will be decided in discussions with the NRL.

"We're going through what we believe our course of action should be and we'll discuss that with the NRL," Robinson said.

"I know people will have their views but for us at this time it's between us and the NRL to resolve."

John Grant, Chairman of the Australian Rugby League Commission, also spoke briefly on the incident.

"It's difficult not to be disappointed," Grant said.

"We need to put this into context, we've still got a great game of rugby league and it kicks off with the Nines next weekend.

"The Roosters are doing their investigation, remembering Mitchell is employed by the Roosters, he is their person, and they'll make a determination, presumably at board level.

"At the end of the day we need to come to an agreement on what is a fair and reasonable way to respond."

When asked if Pearce should be sacked from the game, Grant was non-committal.

"We'll wait and see," he said.

"Clearly I can't make any observation on that."

Video first featured at roosters.com.au

NRL statement on Mitchell Pearce

Sydney Roosters club statement