Security guards have been hired after students were mugged as they left school.
Wellington High School principal Prue Kelly said the attacks were believed to be the work of well-organised gangs.
It is understood other schools in the capital have recently increased security measures to combat the gang threat.
Mrs
Kelly said: "Over the last week we have had security guards because we have had an issue of students being accosted as they leave the school grounds, and attempts made to rob them of whatever valuables they have.
"We've had two kids assaulted. Not badly, but still frightened and assaulted and we've had the police in for them."
The culprits were "unidentified youths" with no links to the school, Mrs Kelly said.
Mrs Kelly said the school already employed "grounds supervisors" from outside the school -- usually parents or people from the community who wanted a part-time job. This was done so teachers could concentrate on teaching, she said.
But last week, security guards were hired and placed on the street on the side of the school where the problems had occurred. Their presence had had the desired result, she said.
Greg Clark, Wellington police's acting sergeant in charge of youth services, said officers were aware of the assaults.
He said: "There are these little gangs hanging around, however we have clamped down on the ones we know are causing problems by varying means that we have."
One such gang was the Strathmore 44s, apparently named for the number of the bus that goes to the suburb of Strathmore, he said. The gang had come to police attention and pressure had subsequently been put on it.
Mr Clark said police were happy to work with schools if they had any concerns.
He hoped recent proactive steps taken by police would help prevent youth gangs becoming more widespread.
Police had gone into secondary schools in the area recently as part of the successful Operation Hurricane which focused on the central city.
"The talks were basically about how if you're one of these gang members or these groups of kids that are out there drinking and causing problems and assaulting other youths in town the police are going to be talking to you," he said.
- NZPA
