Penrith are investigating allegations South Sydney's Greg Inglis was racially abused during yesterday's 18-14 defeat at Panthers Stadium.
In a statement, Panthers CEO Brian Fletcher said the club "has been made aware of an allegation of racial abuse directed at South Sydney player Greg Inglis by a member of the crowd at Panthers Stadium".
"I wish to make it clear our club does not tolerate this kind of behaviour in any form," Mr Fletcher said.
"Any perpetrators will be swiftly dealt with.
"Our club apologises unreservedly to Greg Inglis for the upset caused by the alleged incident."
Penrith prop James Tamou said he was confident those responsible for the abuse would be found.
"I'm pretty disgusted to be honest, to hear something like that," he said.
"I'm pretty confident that the Panthers will put everything behind this and hopefully we find the culprit and deal with it."
Inglis, who is Indigenous, was playing his second game since returning from a knee reconstruction.
He sustained a head injury during the match and left the field to a chorus of boos from a section of the home crowd.
Cronulla's Josh Dugan was not impressed with the treatment Inglis received from the Panthers fans as he left the field.
"When a player is injured show some decency," Dugan wrote on social media.
"We put our bodies on the line as a job, yes, but it's also for your enjoyment and we're all humans.
"GI should never be booed. EVER."