NRL boss David Gallop has endorsed a 20-year ban imposed on a junior footballer for violence amid ugly scenes in an under-16 grand final in Sydney.

A 16-year-old Blacktown City player was suspended from the sport in Australia until 2029 - effectively a life ban - for kicking and stomping in the match on Saturday.

His actions are believed to have left a Lower Mountains player with a broken nose and suspected fractured eye socket.

Two of his teammates were banned for five and another for two years for their parts in the violence in the Penrith and District Under-16 grand final and their coach was sacked.

Vision from the match shows several Blacktown players attacking opposition players and chasing others. Police have indicated it could lead to criminal charges being laid.

Lower Mountains players reportedly sought to avoid confrontation, a decision hailed on Wednesday as "brave" by Gold Coast Titans star Preston Campbell.

Gallop said he was shocked by the violence, which led to Lower Mountains player Miki Hughes being admitted to hospital with severe facial injuries.

He backed the Penrith junior tribunal's hard-line stance.

"What we saw was beyond unacceptable and I'm very comfortable that the sentences handed out are appropriate," Gallop said.

"A strong message needed to be sent and that's what's happened.

"Everyone was shocked to see such graphic violence on the field, particularly from very young kids and they need to understand that's totally unacceptable."

But Gallop dismissed any thoughts on the NRL reviewing its response to all-in brawls and melees at the top level, such as this year's unsavoury State of Origin post-script, as a further deterrent.

"I think the game has taken big steps in relation to the way we see our game on the field and we will continue to do that," he said.

The NSWRL Academy and NRL rewarded the entire Lower Mountains team for their exemplary behaviour in extreme circumstances by giving them free tickets to Friday night's NRL preliminary final between the Bulldogs and Parramatta.

"Every player in the team did everything possible to avoid confrontation and uphold their dignity and sportsmanship with their conduct, behaviour and sportsmanship being an example to all junior rugby league players," said Penrith Junior League manager Don Feltis.

Blacktown City captain Moustafa El-Ali also received praise and tickets for his responsible leadership role during the incident.

Campbell, the 2008 Ken Stephen Medallist for his contributions to the wider community, praised Lower Mountains' response.

"I've always been told to walk away from a fight and I guess that's what they were told and that's not showing any cowardice," he said.

"I think it's braver to walk away."

Campbell admitted he was scared watching vision of the incident and felt 20 years was a just punishment for the worst offender.

"I'm a man who that likes to forgive and forget and I would probably say maybe it's too much but he's kicked a bloke and stomped on the bloke so maybe it was worth 20 years," he said.

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