Seven weeks into the season, the Sydney Combined Competition (SCC) has been rocked by the violence that has lingered long after the final whistle.

NSW Rugby League general manager of Football Barrie-Jon Mather said that following several "unsavoury" incidents, the competition's management committee had issued a "final warning" to more than 60 junior clubs.

"It's sad that we have had to take this action because it's a great experience for 99 per cent of people, we are trying to grow the game and the last thing we want is to put anyone off playing junior football."

But he added: "There has been behaviour we do not want to see continue for the rest of the year. It is best to stamp it out early before it escalates."

The threat to shut clubs out of the SCC follows a move by the Penrith District Rugby League to deploy security guards at its junior games this season, to ensure matches are not marred by unruly parents.

That initiative was the brainchild of Panthers general manager Phil Gould who said yesterday: "This is the single biggest problem around junior sport – and it is not exclusive to rugby league, or this country."

Mr Mather said the SCC, which caters for more than 2500 participants aged 13 and over, could not "point the finger" at any one district because in the space of several weeks, flashpoints had occurred across three leagues. "That's why a letter has gone out to everyone. A zero tolerance policy is in place. We want everyone to come down, enjoy themselves and feel safe at weekends."

A fortnight ago, an under-15s clash between Bondi United and Auburn Warriors was abandoned after a brawl broke out between players at Waverley Oval. NSW Police confirmed that officers from Waverley were called to the scene following an "on-field incident".

But South Sydney Juniors chief executive Luke Curry confirmed the "ugly" scenes did not end there. "The brawl on the field was cleaned up pretty quickly with the game called off towards the end, because of it. But the visiting team would not move on so the police had to come and clear them. Then there were threats made in nearby streets which involved officials, spectators and some of the players."

The Sun-Herald understands that following another "on-field melee" in Canterbury earlier this month, one parent walked onto the pitch and hurled abuse and threats at a trainer. In another episode at a game at St George, two junior sides watched on in astonishment as a coach first "pushed and shoved" a referee over a decision that went against his side. After being escorted from the field, then "lost the plot" and punched an opposition trainer. In the resulting tussle, both men toppled over onto a female spectator, sat close by, who sustained injuries.

One senior SCC source revealed that in another violent act, escalating touchline tension led to one individual threatening another with a pole that was "pulled out of the ground".

"Unfortunately police have been called to a few venues, which for a game of junior football, is very unfortunate," said the source, adding: "We are doing our best to stamp this behaviour out but I must say, it is getting harder to interest parents in having their kids play rugby league because of all this."

NSW Rugby League's community football manager Stuart Stanton said it was regretful a "minority of players, parents, coaches and officials" had lost sight of their responsibilities. In the SCC letter posted to all clubs last week, he wrote: "These people are ruining our game for the vast majority. Quite frankly, we have had enough; If you cannot go to a game of rugby league and enjoy the game for what it is, then you should find another sport."

The letter said there was "no room" for players who "want nothing but to pick a fight", spectators were "not permitted" to enter the playing field under any circumstances and that coaches have no right to "belittle opposition players or their own players".

Mr Stanton also drew attention to the many young referees "walking away from the game" because of touchline abuse, then asked parents: "Do you berate your own children for making a simple error?"

The SCC is not ruling out the introduction of security guards at games, a measure that has restored peace and order to touchlines across the Penrith junior league this season. "There have been a couple of incidents in which guards have had to wave the flag, so to speak," said Penrith Junior Rugby League's Don Feltis. "But generally, we're finding their presence, itself, is enough for potential troublemakers to think twice."

The Penrith league felt compelled to act after a series of incidents across the local district, most notably a near fatal attack that occurred following a game between the Penrith Waratahs and Western City Tigers under-19 teams in 2013. Eight players, all from the Tigers, received bans of up to 25 years for punching and kicking offences.

One of the victims that day was Waratahs player Jake Weekes who kicked the winning penalty goal in extra time, only to then have his head stomped on by opponents. Graphic images captured by Fairfax Media showed the moment Tigers players had their feet raised above his head. Weekes revealed yesterday that he has still not returned to the sport he loves: "I go and watch on the sidelines sometimes but have taken a couple of years off."

He said he understands it "sometimes get heated" on the field but added: "At the end of the game, it should always be about shaking hands and about sportsmanship. I'm not sure how things got so bad."