A teacher at Marlborough Boys' College is being investigated after a complaint was made regarding conduct that is believed to have taken place outside of school hours.
Newshub understands the complaint does not relate to any behaviour that involves a student and has chosen not to publish the allegations while the investigation is ongoing.
On Tuesday, Marlborough Boys' College Principal John Kendal told Newshub he was aware of an investigation that began earlier that day.
He said the teacher had not been stood down. In a statement supplied later that afternoon, a school spokesperson told Newshub the teacher is currently on leave.
"The person concerned is on leave and the matter is being investigated but as you will understand we cannot comment further on anything related to the employment relationship.
"We can confirm we have informed the Ministry of Education as it is important to us that all matters are handled appropriately."
On Wednesday an email, supplied to Newshub, was sent out to parents emphasising student safety was not a concern.
"I would like to inform all parents and caregivers that yesterday we received a complaint about a member of staff.
"The matter is not related to the students or the school but we take it seriously and the person concerned is on leave while it is being investigated.
"As you may be aware we cannot comment further on anything related to the employment relationship but we wanted to let you know this information in case the matter became public at this early stage of our process.
"We can confirm we have informed the Ministry of Education and Teaching Council as it is important to us that all matters are handled appropriately.
"While we know that this email doesn't provide much detail, we hope that it gives you confidence that we have good processes, that we take complaints/issues seriously and that we act promptly to respond to them."
In a statement, Deputy Secretary Sector Enablement and Support Helen Hurst told Newshub the Ministry of Education is aware of the complaint and has been in contact with the school.
"We strongly encourage anyone with concerns to contact the police or the school board, who will liaise with the appropriate support agencies, including the Ministry if required."