Party-goers and concerned police will be given just 24 hours' notice of the venue for an unofficial school ball.
The unofficial Wellington school ball will go ahead tomorrow, with the venue set to be announced this evening.
Sergeant Damian Rapira-Davies said police were "aware of plans to hold a privately-run school ball tomorrow night in Wellington".
"Police have learnt of the intended venue for the function late today.
"Police are concerned that this event has had a history of problems in regard to under-age drinking and harm to party-goers. The safety of those attending the function is a priority for police."
A police spokeswoman said they were "not in a position to share the location for the planned event".
Last year an unofficial Wellington College ball organised by students without the school's permission left 37 students requiring treatment for alcohol-related issues, and 11 injured.
Former Wellington College student Hugh Soper is this year's ball organiser and he posted on Facebook that tickets were on sale for the event, but it was not associated with any school, Fairfax reported.
"Location is in central Wellington and full disclosure of the location will be said [on Friday] night," the post read.
A ball had been scheduled to take place in the James Smith Corner basement in late September, but that was scrapped after police said the venue's licence meant every attendee under the age of 18 would need to be accompanied by a parent.
Wellington College headmaster Roger Moses told Fairfax that the school "completely dissociates itself from any private function organised by any individuals, whether they be parents or students". The school has not had a ball for about 25 years.