As well, a drunk 13-year-old girl was taken home to her parents.
Southern police district operations manager Inspector Dave Miller said more than 100 police officers stopped 8369 motorists, made 172 hotel visits and took to the streets to check liquor-ban compliance on Friday and Saturday nights across Otago and Southland.
The operation was part of the fifth Operation Unite, a transtasman police operation targeting alcohol abuse.
Across the region, 7567 drivers were breath-tested at checkpoints, with another 802 people stopped and tested by mobile police patrols.
Eighteen people were charged and 29 others warned for breaching liquor bans.
City staff and the rural drink-driving squad helped with checkpoints in Dunedin and Invercargill, while there were additional patrols in rural areas and checks on pubs and liquor-ban areas.
Senior Sergeant Phil McDouall said in Dunedin, 298 mobile breath tests were done, and 5901 motorists were tested at checkpoints.
Of those, 237 breath-screening tests (where people stopped gave an indication of alcohol on their breath but test showed under the limit) were done, and nine people would be charged with drink-driving.
The highest reading was 1016mcg. The limit for people aged over 20 is 400mcg.
One disqualified driver was stopped. A total of 163 tickets were issued.
Nine hotels were visited, with no breaches of liquor laws recorded.
Three underage drinkers were found in the city and a 13-year-old girl found drunk was taken home to her parents.
Across the wider region, one on-licence and one off-licence were found selling alcohol to minors from eight controlled-purchase operations.
Across New Zealand, 987 people failed breathalyser tests, 578 licence breaches were detected and more than 2000 people were charged with alcohol-related offending.
Assistant police commissioner Nick Perry said coming into Christmas it was timely to think about alcohol and behaviour and "how we can do better and look after ourselves and each other".
"Unfortunately, alcohol remains a common factor in a wide range of offending and victimisation," Mr Perry said.
"On an average day in New Zealand, there are 49 incidents where a person is either driven home or is taken into police custody due to their intoxication level and 253 apprehensions where offenders have consumed alcohol prior to their arrest."
Operation Unite
100 police officers
25 drink-drivers
5 hotel Liquor Act breaches
18 alcohol-related arrests
30 liquor-ban warnings
