League referees say the problem of violent spectator behaviour fuelled by alcohol has been escalating alarmingly.
Canterbury Rugby League Referees Association acting chairman Mike Glover said the security guards were hired after a plea for league bosses to protect match officials.
Mr Glover declined to discuss Saturday's incident because it was under investigation and due to be discussed at a referees' meeting last night.
But he said referees and match officials were becoming increasingly concerned for their safety in the face of drunken and unruly spectators.
"Some incidents I've seen in the last 12 months have been the worst in the 30 years I've been involved in rugby league," Mr Glover said.
"We've had some games at [suburban] grounds where the behaviour from spectators has been appalling."
Mr Glover said there was "a big problem with alcohol on the sidelines inflaming spectator abuse".
He put the issue down to the loss of Rugby League Park at Addington, which sustained significant damage in the February 2011 earthquake and was redeveloped as a rugby stadium.
"Officials there were able to ensure no alcohol was taken into the grounds," he said. "Now it's open slather. People can buy their dozen beer and drink it on the sidelines."
Mr Glover called for an alcohol ban at sports grounds between 9am and 4pm on playing days.
Sport Canterbury chief executive Geoff Barry said he knew of no other sporting code hiring security guards.
However, he was aware that Canterbury Rugby League was "having challenges".
Mr Barry said there would always be "the odd punch" among players in any contact sport.
"The fundamental issue is around not only player behaviour, but also spectator behaviour," he said.
"As soon as spectators become involved it becomes a more serious issue. It's sad for sport."
- APN