Aproximately 30 people were arrested in the early hours of this morning after riot police clashed with a crowd on Dunedin's Castle Street, a well-known student area.
The arrests followed a trouble-free day as students associated with the unofficial Undie 500, a Christchurch to Dunedin car run, partied around the city.
Inspector Lane Todd told NZPA police and the fire service were called to an incident involving a fire just after midnight.
Around 300 people had gathered on the street and some bottles and rocks were thrown at police.
Mr Todd said police broke up the group and had cleared the road and dispersed the crowd within an hour.
The incident was minor compared to the riots last year when 69 people were arrested following the last official running of the Undie 500, Mr Todd said.
He said police had not yet processed all the details of the 30 arrested, so could not say whether they were locals or those associated with the Undie 500.
The arrested will face charges of assault, obstruction and resisting arrest and have been bailed to reappear in the Dunedin District Court on Thursday.
The authorised Undie 500, organised by Canterbury University engineering students, was cancelled this year, after last year's riots and arrests.
Overnight Friday three Canterbury University students and two from Otago were arrested and charged - four for disorderly behaviour and one for wilful damage.
A group of about 40 rebel vehicles left Christchurch on Friday for Dunedin, defying the ban on the event.
Last year more than 150 vehicles took part.
The event involves students driving from Christchurch to Dunedin in cars bought for less than $500.
Officers from Christchurch shadowed the procession as it travelled between the cities and remained in Dunedin over the weekend to help out if needed.
A temporary liquor ban was imposed for the first time in the student area of North Dunedin in order to reduce trouble.