Sixteen known gangs are operating in the South, police have revealed.
But the news came after initial hesitation from police to release the information, citing concern it could lead to "intergang rivalry" and an increase in serious offending.
That excuse, according to a leading New Zealand gang expert, was "nonsense".
The Otago Daily Times requested a range of information about gang activity in the Southern police district, including how many known gangs were present in the area.
It followed revelations that the number of gang members and prospects in Otago and Southland has risen 61% in less than two years.
In October 2017 there were 134 patched gang members or prospects in the district. By the end of August this year, that had increased to 217.
Police said gang members were peddling drug-related harm in the area. But they were less keen to say how many gangs were present in the district.
Citing privacy, prejudicing the ability to maintain the law, and the impact on the supply of information, police also initially withheld the information to prevent "the provocation of inter-gang rivalry, and an increase in serious offending".
Gang expert and University of Canterbury Prof Greg Newbold called that response "absolute nonsense".
He believed the reason for the initial refusal was that police were not exactly sure how many gangs there were.
"Patched gangs, they’ll know about some of them, but they won’t know about the homie gangs, the street gangs, the kids who hang about under a name.
"Nobody knows how many of them there are, because they come and go."
Following questions from the ODT about the reasoning, police admitted they had been wrong to withhold the information and apologised for the error.
There were 16 gangs known to be operating in the area, police said.
While exactly which gangs they are remains unclear, Otago Coastal Area prevention manager Inspector Wil Black previously said the Mongrel Mob was still the biggest gang in Dunedin "without a doubt", and it also had a strong base in Mataura.
But the city had a "splattering" of most gangs, including Black Power and the King Cobras.
Criminals deported from Australia had also been added to gang ranks, and brought with them more sophisticated operations and networks throughout New Zealand, Australia and Asia, he said.
