The principal of St Peter's School in Cambridge has resigned amid an investigation into bullying at the school prompted by a number of complaints to Worksafe.

A school spokeswoman this afternoon told the Herald principal Dale Burden had resigned, effective tomorrow, but would not be returning to the school.

Earlier this month questions arose about the absence of Burden and his wife, and deputy principal, Yevette Williams who had not been seen at the school since before the end of the first term.

The Herald understands Williams is still away from school.

The spokeswoman said the school was unable to make further comment.

The board of the private Waikato-based school earlier confirmed earlier that bullying complaints had been made to workplace bullying watchdog WorkSafe in term 1.

WorkSafe said it was making inquiries about "staff wellbeing" at the school amid the absence of Burden and Williams.

Worksafe yesterday told the Herald more people had approached Worksafe since media coverage of the allegations earlier this month.

Board chairman John Erkkila said WorkSafe had contacted the board in term one that anonymous complainants had made concerning allegations of workplace bullying and that WorkSafe was making inquiries.

"Following a meeting with WorkSafe, we worked to understand the best course of action and the board engaged two independent investigators.

"Those investigators have sought to understand what may or may not have occurred. Those investigations are not yet complete, but I want you to understand that this issue is being taken incredibly seriously.

"And I want to understand, if any wrongdoing is found, how that was allowed to happen and how we go about ensuring it doesn't happen again," he said.

The Herald can also reveal the investigation was being headed by former chief judge of the Employment Court Graeme Colgan.

St Peter's School in Cambridge. (Photo / File)

In the email to parents sent out after Worksafe confirmed it was involved, Erkkila acknowledge the slow release of information to parents and caregivers.

"As a board, we have legal obligations and for that reason it has been a difficult environment to navigate. But I also recognise the need to be open as possible with our school community is important."

He added that the investigations were still under way and the board "cannot and will not pre-determine that".

"But if it is deemed that workplace bullying has occurred, I want you to know that it will be addressed.

"I cannot and will not allow bullying of any kind in our workplace. Being on the receiving end of bullying behaviour is incredibly damaging to a person's mental health and it will not be tolerated, now or ever.

"If there has been or if there is still workplace bullying happening, we need to know so it can be stopped."

Operational matters were in the hands of chief operating officer Rob Campbell during the investigation, while teaching and learning matters would be looked after by campus principal Julie Small.

Burden joined the elite Waikato school in 2016 after a decade as headmaster of Mt Albert Grammar School in Auckland.