The president of the Post Primary Teachers Association has called for more Government support for schools to combat bullying.
His comments come after the Ombudsman's Office yesterday issued its findings after its investigation into bullying at Hutt Valley High School in 2007.
Reported incidents include a group of six teens ganging up on Year 9 students during lunchtimes, dragging the students to the ground, removing their pants and violating them with screwdrivers, pens, scissors, branches, drills and pencils. Other incidents include a student being beaten unconscious and a student being burnt with a lighter.
Ombudsman David McGee recommended schools' guidelines be amended to make anti-bullying programmes compulsory in schools.
"This is because the situation at Hutt Valley High School demonstrates that the lack of appropriate sanctions can contribute to, and risk normalisation of, a culture of violence."
He said a rigid national template for school discipline would have little merit, but the current "entirely discretionary" system risked producing arbitrary disciplinary decisions within and between schools.
PPTA president Robin Duff said the report illustrated a systemic failure by the Ministry of Education and the wider government to support schools with bullying.
He said bullying was not an issue only at Hutt Valley high School, and "teachers across New Zealand have asked for help with student behaviour for years".
"Dealing with difficult students requires a range of government agencies to work together. It requires a sophisticated level of collaboration and leadership and adequate funding."
"Intervention should occur as early as possible and PPTA want to see the implementation of evidence-based programmes coordinated by the state agencies involved".
Mr Duff said there was a lack of transparency from schools due to competition from students.
"No one is going to put up their hand for help if it meant negative messages in the media that could threaten its enrolment numbers," he said.
"The ministry pressures schools to keep students at school knowing that it is putting other students and teachers at risk because it has nothing realistic in place that works to tackle bullying."
Mr Duff said the safety of teachers is paramount, and the association advise teachers not to work in areas of the school where they feel unsafe.
The acting principal of Upper Hutt High School said back in 2007 he had no regrets about how the incident was handled and "it wasn't an assault where somebody had spilt blood".
But the school's board of trustees yesterday apologised "unreservedly" for the way the incidents were handled.
"The boys involved and their families were let down by the school.
"The 2007 incidents were a hard lesson for the school. At its core, we did not look after the victims' and their families' interests nearly well enough."
The board said the school had changed its practices towards social education.
While the report called for mandatory anti-bullying, Schools Trustees Association president Lorraine Kerr said schools already had systems, and a mandatory anti-bullying programme might do more harm than good.
"Based on the lack of action of one school, all schools are being charged with their mistake. In fact, every other school has had behaviour management programmes in place in one form or another."
"It's not a one-size fits all situation - what works in a school from a nicer area might not work for one from an area which has gang problems, for example."
Education Minister Anne Tolley said the report highlighted some serious issues but there had been significant changes since the incidents took place four years ago.
The Government had put $60 million into the Positive Behaviour for Learning plan.