North Queensland police were called to a junior rugby league final after it descended into an all-in brawl in Townsville yesterday.

The incident took place at the under-15s grand final between the United Suburbs Redbacks and Western Lions, which witnesses said turned ugly when the mother of a player ran onto the field and allegedly assaulted a player over the way he tackled her son.

A witness said more than 200 spectators, players and parents ran onto the field and began fighting until dozens of police officers arrived.

"There was about 30 seconds left in the match and one of the players slung him around and then landed on top of him," the witness said.

"And then it turned into a brawl and next minute you know the parents and spectators started getting involved.

"One lady got king hit from behind by a bloke and then everyone started chasing him. It just kept on going."

Another witness said it was the biggest fight he had ever seen at a junior rugby league event.

"One lady ended up slapping a copper when they were interviewing people ... she got arrested straight after that," he said.

"Someone videotaped it and those people will be dealt with. They ended up cancelling two games I think."

Supporters said they were threatened with long bans from the game if they gave video footage of the brawl to the media.

A spokesman for the Townsville and District Junior Rugby League said the result of the match had been suspended pending an investigation into what happened.

An official complaint has not been made to police but the local rugby league association is dealing with the matter.