Associate Education Minister David Benson-Pope has been hit by claims he jammed tennis balls in boys' mouths and smacked one so hard his nose bled while working as a teacher.

The accusations, made by Act and National under parliamentary privilege yesterday, were rejected as "disgraceful" by the minister.

The principal of Bayfield High School, the Dunedin school where Mr Benson-Pope worked when the assaults allegedly took place, labelled the claims "preposterous".

Bruce Leadbetter, principal during much of Mr Benson-Pope's time there, also dismissed them.

The claims, believed to relate to the 1980s, come as the Government is under siege for its handling of education on numerous fronts.

Act leader Rodney Hide used the minister's unveiling of an anti-bullying campaign on Monday as background to the claims.

He asked Mr Benson-Pope: "Is it correct that he used to cane students particularly hard while at Bayfield High School and throw tennis balls at them if they misbehaved. If so how can he have any credibility in speaking out against bullying?"

Mr Benson-Pope said he had used corporal punishment in line with the school's then policy.

"But I've come to believe that corporal punishment is a totally inappropriate form of discipline."

National MP Judith Collins asked: "Did he ever tie boys' hands together and jam a tennis ball into their mouths as punishment for talking when he was a teacher?"

"I find such allegations ridiculous and I refute them," Mr Benson-Pope replied.

Mr Hide then asked: "Did he ever smack a pupil with the back of his hand sufficiently hard enough to make his nose bleed at a school camp in the Catlins and is this the reason along with throwing tennis balls at pupils in the classroom that he has the reputation of being a terrible bully and in fact the students to this day still suffer from his treatment?"

"That is a disgraceful allegation and I refute it completely," Mr Benson-Pope replied.

Such behaviour was "clearly illegal" and if Mr Hide had any information he should take it to the police, the minister said.

"I have not been guilty or involved in any inappropriate behaviour, nor am I aware of any complaint of any kind."

Helen Clark, not in the House yesterday, said through a spokesman she had not previously been advised of the allegations.

"She accepted Mr Benson-Pope's word that they were unfounded and that they continued a series of scurrilous accusations from the Act leader," he said.

Mr Benson-Pope headed the high school's languages and outdoor education department and resigned in late 1998, entering Parliament in 1999.

Bruce Leadbetter, who retired just after he left, was principal there from the early 1980s.

He said the claims were "idiotic".

Mr Benson-Pope was "certainly strong on standards" and took a "very hard line" on discipline and safety while running school camps, he said.

But he was not aware of any complaints Mr Benson-Pope had ever crossed the line.

Together with current principal Denis Slowley he was scathing about what he considered Mr Hide's abuse of parliamentary privilege. He spoke to teachers at the school who taught with Mr Benson-Pope who labelled the claims "preposterous".

Mrs Collins would not repeat her allegations outside Parliament.

Mr Hide was careful not to repeat them, saying: "I didn't ask those questions lightly but the rules of Parliament mean that I have to accept the minister's word, but boy, if he's wrong he's a goner."

Asked if he would take the allegations to the police he said: "I'm in a position where I have to accept the minister's word".

He had spoken to a "number of people" about the allegations. Asked if they would go to the police he said they were "still considering their options".