"This practice goes against the Sale and Supply of Alcohol Act of 2012," Snr Sgt Bond said.
Specifically, it violated section 237 of the Act, which dealt with the "irresponsible promotion of alcohol".
"Our main concern was promoting excessive alcohol consumption among young and vulnerable students."
Alcohol manufacturers had been warned and police would be on the watch again this year.
The university's proctor office worked closely with police and Safe and Well Otepoti to combat the exchange of booze for advertisements.
Proctor David Scott said it happened throughout the year, but mostly during Orientation and Reorientation Weeks.
"Alcohol manufacturers have agreed not to repeat their behaviour.
"No students were disciplined," Scott said.
University of Otago (Christchurch) psychiatry and addiction medicine Professor Douglas Sellman said the practice of swapping alcohol for advertisements was as unethical as it was dangerous.
"Alcohol is not a neutral product.
"It is neurotoxic, aggressigenic and carcinogenic," Sellman said.
Alcohol needed to be regulated to limit the damage it inflicted on communities, not given away to students, he said.
The university's ban on alcohol advertising was a good but mostly symbolic gesture.
Instead, the university needed to do more and hold and subsidise interesting and fun non-drinking events with food, music and other entertainment.
"This way the university would demonstrate how O Week could be a safe, instead of the chaos of an alcohol-fuelled Disorientation Week that it is for many."