South Sydney coach Jason Demetriou erupted in his post-match press conference on Thursday night following an alleged spat of racial abuse directed at Latrell Mitchell from teenaged fan.

The abuse is said to have occurred as Mitchell left the field at half time of the Rabbitohs' 16-10 loss in Penrith.

Teammates and opposition player Jerome Luai reportedly rallied around the 25-year-old star in the race.

In a statement after the match, the Panthers said they were aware of the incident and had immediately informed the NRL.

Police are understood to be investigating the matters.

The Rabbitohs' coach was quick to squash any doubts around whether the matter occurred.

"It's not a claim. It happened," Demetriou said in his press conference.

"It's not the first time we've come here as a club and our players have been racially abused. Where does it end? It's just not on.

"I shouldn't have to come here as a coach and lead a team of players in here to be racially abused. It's not really a part of our game today and we have to stamp it out completely."

Demetriou said he "can't understand how that happens in our day and age" and called for stronger response from the league to address racist behaviour.

"Life bans. Anyone wants to make racial abuse and get them out of the game. We don't want their support. It's got to end," he said.

"He (Mitchell) should be able to come here as a star of our game and not be racially abused.

"I can't get my head around how a young kid thinks that that's the language to be using…Get them out of our game.

"I don't understand how in Australia anyone is raised like that.

"I just get worried about Latrell or any Indigenous player now in our organisation.

"There has to be hard and fast rules if anyone even comes close to being racial they are completely ruled out of our game. And if it's a young kid, rule his parents out as well. It's just not on."

Demetriou said racism is something a lot of people have never had to endure and will not understand but needs to end.

He said he would be "ashamed" if it was his child saying those things.

It's not the first time Mitchell has been subject to racial abuse.

The 25-year-old has been involved with campaigns and led his own messaging on stamping out this kind of behaviour.

Mitchell has also been a magnet for various levels of criticism, including those at his performances and personality, over his career.

Now there are fears the abuse could see the Wiradjuri and Birrbay man walk away from the game.

In September 2022, Mitchell likened the constant booing he received from opposition fans in the stands to those which saw AFL star Adam Goodes unceremoniously driven out of the sport after a decorated career.

Mitchell has already flagged a potential to swap out football for a lower-profile life on his Taree farm when his current contract expires in 2027.

On Friday the Sydney Morning Herald reported Rabbitohs and NSW teammate Damien Cook harbours concerns of a star career cut short.

"This is why he (Mitchell) might talk about being done at 30," Cook told SMH.

"We have a great player who puts bums on seats, everyone wants to see him play, but when you get things like this, and when it comes to a time to choose farm or footy, these things come up.

"He leads so well by example for the Indigenous culture and the young kids coming through, it's an absolute joke it's happened. And why?

"It's 2023 and this is happening. This isn't the first time Latrell has had to go through this."

Cook said he caught the end of the scenes on his way to the sheds and witnesses the number of players try to identify the young fan who committed the act.

Demetriou said it's a testament to Mitchell he is able to come out each week and face the attention he receives.

"Latrell answers his critics with his character every week. He just continually shows the quality person that he is," he said.

"This is not something that Latrell just cops on the footy field, this is something that he's had to deal with his whole life. All Indigenous people do.

"Latrell is a role model in our game, we love him at a club, he stands for Indigenous people and he stands for good people.

"He'll handle it and we'll handle it. We'll support him as a club. But he shouldn't have to handle it. He shouldn't have to keep dealing with this. It's just rubbish."

Later on Thursday the NRL released a statement confirming the incident is being investigated by their integrity unit.

"Any form of racism or vilification will not be tolerated in our sport. We will not accept this behaviour from anyone," NRL chief executive Andrew Abdo wrote.

"We are working with the stadium and the club to get all the facts.

"We will stand behind our players and commend them for calling out this behaviour."