NRL chief executive Todd Greenberg has warned Ben Barba he could face a life-time suspension from the competition after he was sacked by North Queensland Cowboys.

Barba was axed on Friday following a "significant breach" of his contract, with reports alleging he was involved in a domestic violence incident at a Townsville casino.

The former Dally M Medallist and 2018 Super League Man of Steel was preparing to make his first NRL appearance since 2016, having been sacked by Cronulla Sharks following a positive drugs test.

Fronting the media on Saturday, Greenberg said the 29-year-old – who has not been charged with an offence by police – may never play in the NRL again if allegations are proven.

"We have run out of patience and tolerance for misbehaviour off the field. I'll repeat again that violence against women is at the very top of that list," Greenberg told reporters.

"If you're violent against women you can expect to be removed from the game. That starts now.

"The Cowboys overnight have acted quickly and decisively to terminate Ben Barba's contract. That's a club showing the leadership that's required.

"If [the CCTV footage] shows violence towards a woman, than really there's no debate. Ben Barba will be out of the NRL immediately and I can't see him ever returning. Certainly, if the evidence is there he won't return under my watch."

"I issue this warning to players again," Greenberg said. "The game has changed and community expectations are clear. We won't tolerate misbehaviour and the sanctions will be strong, especially for violence against women.

"We had a brilliant 2018 on the field, but quite frankly the off-season has been a complete train wreck. We must protect the game."