Footage of a brutal attack at Otago Boys' High School has spread rapidly around Dunedin and been labelled "incredibly upsetting" by outraged parents.

The graphic cellphone video shows a defenceless pupil being cornered in a school bathroom and repeatedly punched, kicked and shoved in a vicious assault by two other boys.

The attack happened last Wednesday and has since been shared widely through social media and across schools.

Otago Boys' acting rector Andrew King said the school took the emotional and physical safety of pupils "extremely seriously".

"We have a zero tolerance for unacceptable behaviour in our school environment."

The actions of the pupils involved were being managed through the school's formal disciplinary process at a board level and support was in place for all pupils involved, he said.

"We assure our school community that this incident is being dealt with appropriately."

Footage of a brutal attack at Otago Boys' High School has spread rapidly around Dunedin. Photo / ODT

The 67-second clip starts with two pupils aggressively cornering the victim between the wall and a bathroom stall.

One of the attackers turns to the camera and smiles, followed by the victim asking "why are you doing this?"

The other assailant responds instantly with a left-handed sucker punch to the victim's chin.

The first attacker turns back towards the camera and encourages the cameraman to join in, who declines and says he does not have a problem with the victim.

The boy is struck again and then pulls out his wallet, seeming to offer it to the attackers.

"I don't wanna fight," he tells them as he sways, appearing to lose balance after suffering another blow.

He is punched twice more in quick succession, knocking his head against the wall once.
The victim tries to walk away using the wall to balance and is kicked in the leg.

The initial aggressor re-enters the fray and inflicts two forceful right-handed punches, slamming the boy's head into the stall with an audible thud.

The victim staggers off and defends himself for the first time, blocking a punch, as the attackers kick at his legs and try to shove him down.

They go to block his path and threaten him.

"You won't f***ing snitch aye? You won't f***ing snitch?"

The victim starts to walk away and the video ends.

The Otago Daily Times was contacted by parents of pupils at other schools, to which the video had spread.

One said the footage was "incredibly upsetting" and she wanted to know something was being done about it.

Another said he could not sleep after seeing the video.

King was disappointed it was being shared and asked people to be mindful of the ongoing harm caused to those involved.

"While we are dealing with the incident in the present, the re-harming through sharing on social media is much harder to deal with."

The school asked community members and parents to speak to their children.

"We are committed to continuing to work with our community to ensure our students are safe."

A police spokeswoman said they had received a report of a serious assault at the school on June 15 and were making inquiries.

- Wyatt Ryder, ODT