Three Nelson College students have been suspended or stood down from boarding over "serious acts of bullying".
A statement from headmaster Gary O'Shea and Board of Trustees chairman Dennis Christian said the school was dealing with serious disciplinary incidents which occurred in term one and involved 13 boys, three of whom were Year 13 students.
The senior administrators were only made aware of the issue last week.
The statement said the investigation resulted in one Year 13 student being removed from boarding and suspended from school pending a Board of Trustees hearing. Another Year 13 student was removed from boarding and sanctioned while one was stood down from boarding and sanctioned.
It was not clear what the sanctions involved.