North Queensland halfback Robert Lui has been stood down indefinitely by the NRL club after pleading guilty to an assault charge.

Lui was placed on a two-year good behaviour bond and fined $2000 in Sydney's Burwood Local Court on Wednesday for assaulting his girlfriend Taleah Rae Backo following Mad Monday celebrations in September last year.

The 22-year-old signed with the Cowboys on November 9, and has been taking part in counselling sessions since arriving in Townsville.

Cowboys chief executive Peter Jourdain said it was not yet clear how long Lui - who came off the bench in the opening-round loss to Gold Coast - would remain suspended.


"The length of his suspension will be determined in due course with his rehabilitation remaining a high priority,'' the club said in a statement issued on Wednesday afternoon.

"Before we signed Robert, we were aware of this pending charge and he admitted he had made mistakes in his life.

"Since Robert has been with the Cowboys, he has been an exemplary trainer, a fine contributor to our club and has clearly indicated he wants to make a fresh start with us.

"However, in conjunction with the NRL, the Cowboys have decided to suspend Robert from playing indefinitely after he pleaded guilty today.''

NRL chief executive David Gallop said the Cowboys had little option but to stand Lui down.

"We have spoken to the Cowboys today and asked them to provide a full report as to their intended action as well as the progress of the counselling program that has already commenced,'' Gallop said in a statement.

"We will assess that but, at this stage, Robert won't be playing footy.

"Every case needs to be taken on its merits but a conviction involving violence against women is an issue that we take extremely seriously.''

The assault occurred following the Tigers' Mad Monday celebrations after the team had been defeated by the Warriors in a semi-final the previous Friday night.

Magistrate Glenn Walsh said he believed Backo's evidence that Lui had kicked her in the temple, causing bruising and swelling to her face.