The Corrections Association of New Zealand (Canz) said members of the "Crips" gang were responsible for two recent assaults at the prison, one last month and another last Monday.
In the latest assault — labelled by the union as "cowardly and unprovoked" — an officer was taken to hospital after being struck on the head by an inmate.
A source, who wished to remain anonymous, said a member of the gang was also responsible for an earlier attack where two prison officers were taken to hospital after they were assaulted on April 15.
Data provided to the Otago Daily Times shows the number of prisoners at Otago Corrections Facility associated with the Crips has more than tripled from 16 in 2019 to 53 as of the end of last month.
University of Canterbury senior lecturer and author of Patched: The History of Gangs in New Zealand, Dr Jarrod Gilbert, said the Crips were a form of a Los Angeles street gang that established in New Zealand during the 1990s, before becoming more prominent in the 2000s.
"They tend to be hyper-materialistic and hyper-violent, and largely made up by youths."
The Crips differed from gangs with New Zealand origins by not wearing the traditional back patches and being loosely tethered together rather than adhering to the formal structures that gangs such as Black Power or the Mongrel Mob do.
"[The Crips] have grown into quite a significant group."
Dr Gilbert said members of the Crips gang might be more violent while incarcerated because of their youth and the hyper-violence that was typical of the gang.
"LA-style street gangs are the most violent form of gang statistically. Those less mature gangs are looking to make a name for themselves and the membership is younger.
"Younger people tend to be more violent in prisons."
Otago Corrections Facility general manager Dave Miller said as of June 30, the prison population was 427, with 243 prisoners connected to gangs.
Of those, 53 were associated with the Crips.
"They are not the prominent gang on site at Otago Corrections Facility."
