Police have been forced to use capsicum spray after several brawls broke out during the Moomba Festival on Saturday night.

Police have confirmed they arrested five people following three separate brawls between two groups of youths at Federation Square and Flinders Street Station between 10pm and 2am.

Three people were arrested for assault and two people for drunken behaviour. Two penalty notices were also issued, one for riotous behaviour and one for weapons offences.

Victoria Police spokeswoman Alex Day said the three brawls appear to have involved the same two groups of youths.

"It’s understood on each occasion two groups of youths began fighting before both Public Order Response Team and uniform police immediately intervened ... Police believe the three fights are linked," she said.

She said an increased police presence in the city because of the Moomba Festival allowed a rapid response to the violence and that capsicum spray was used on two occasions to break up the fights.

Police are still investigating the incidents and an increased police presence will remain in the city throughout the remainder of the Moomba Festival which finishes on Monday night.