NRL boss Todd Greenberg has vowed to "throw the book" at the person who is alleged to have racially abused South Sydney star Greg Inglis during their NRL match against Penrith.
The NRL integrity unit and the Panthers are investigating claims a member of the Panthers stadium crowd called Inglis a "black dog" at the end of the match on Saturday.
"My take on it was appalling. It's disgusting," Greenberg said on Monday.
"I don't have to say the type of things that our game does around being inclusive and the work we do in indigenous programs. The work we've done over a number of years speaks for itself.
"Great crowd there on Saturday, great game of footy, (but) it's particularly disappointing that one person can spoil some of those headlines."
Greenberg praised Penrith for reacting swiftly on the incident, with the club expected to identify the person over the next 24 hours.
Greenberg, who revealed he had spoken to Inglis on Sunday, shied away from the possibility of a life ban but insisted the person would be adequately punished for their actions if found guilty.
"I give the Panthers club, people like Brian Fletcher and Phil Gould an enormous wrap for working effectively round the clock for the last 48 hours, trying to find this culprit," he said.
"And if we do, we'll throw the book at him.
"The message is simple: we don't tolerate that sort of behaviour. Nor does community, or rugby league, more specifically.
"You're not welcome in our game. You're not welcome to be part of the game. In fact, you aren't part of the game. If and when we get to that point in time, we'll make those decisions."
Kangaroos coach Mal Meninga said he was angered by the incident.
"We thought racial vilification has gone out of our game, obviously it hasn't," he said.
"I reckon Greg will be hurting. I applaud him for his actions and hopefully they find the perpetrator and kick him out for life."
The Panthers have also denied reports utility Tyrone Peachey was racially vilified in the same game.