Nelson College is devastated after a senior student was suspended and two others sanctioned following "serious acts of bullying", the school's headmaster says.

Photo: RNZ / Tracy Neal

Headmaster Gary O'Shea said the college had removed two students from one of its boarding houses and stood down another.

He said one of the students was suspended from school and two others sanctioned following an investigation into what amounted to "serious acts of bullying".

Mr O'Shea said the incidents at Fell House happened in the first term this year, but were only reported last week.

He said the incidents involved 13 students - three of them seniors - and have had a negative impact on some junior boarders.

Mr O'Shea said the college was considering police action.

Bullying has always been a problem, former student's father says

A father who said his son was bullied while boarding at the college said he was disappointed the behaviour was continuing, despite efforts by the school to stop it.

Photo: RNZ / Tracy Neal

The man, who RNZ cannot name to protect the former student, said he was worried the effects were worse now than in the past.

"You talk to some of the old boys there, and some of the stories you hear from them - it's always been going on," he said.

"[There's] probably a bit now because they get a bit more sneaky, don't they, they can do it through their phones."