Police are investigating a brawl last night between rival rugby league fans during an NRL finals match in southern Sydney.

Supporters traded blows during the Cronulla Sharks versus Sydney Roosters elimination final encounter at Shark Park.

Police and stewards were forced to step in to separate the brawling fans inside the stadium.

NSW Police said in a statement today that investigations have started.

“An investigation is underway after a brawl involving up to 10 people broke out within the grounds of a football stadium in Cronulla last night.

“Police have commenced inquiries into the circumstances surrounding the incident.”

The NRL said they were working with authorities to find those responsible, and threatened bans to anyone found guilty of offences.

“The NRL is working with both the venue and NSW Police regarding the incident. All supporters who attend NRL games are subject to the NRL Spectator Code of Conduct”, an NRL spokesperson told 9News.

“Anyone found breaching the required standards can expect to be subject to significant sanctions, including being banned from venues.”