Up to 40 people were involved in the fight, which took place outside Walsh's Hotel on Monaro Street about 6pm.

The brawl, described by police as a ''major incident'', spilled out across the street and blocked traffic.

Queanbeyan Police inspector Chris Varley said officers arrived at the pub ''en mass'' and arrested six people.

''We did have a lot of additional resources rostered for [Anzac Day], just in case such a thing would occur,'' Inspector Varley said.

''We then intervened in several running fights and brawls that were taking place involving about 30 to 40 people,'' he said.

''Monaro Street was basically blocked off and vehicles were not getting through.''

Inspector Varley said backup was called in from Bungendore and Captains Flat to help break up the fight.

''For those people that's a 30 or 40km drive before they can get here,'' he said.

''It's disappointing that the behaviour was such that it deteriorated into an affray.''

He said there were no major injuries, but said staff at Walsh's Hotel were concerned that glasses or bottles might have been used as weapons.

''The police concerned did a very good job to tidy up the mess, given the amount of people involved,'' he said.

''It was pretty frightening stuff.''

The licensee shut down the pub after the brawl, according to police.

Inspector Varley said the root cause of the brawl was obvious.

''Alcohol, and people having too much of it,'' he said.