Sam Uffindell: Tauranga MP admits he should have disclosed his past, before standing in by-election

National MP Sam Uffindell said there was a culture of "rough and tumble" when asked if he had been involved in any other incidents of bullying as a schoolboy.

Aged 16 as a Year 11 student at King's College, Uffindell and three others jumped on the then 13-year-old boy and began beating him with what was believed to be unscrewed wooden bed legs.

"Boarding houses in the 1999, there was a bit of rough and tumble that went on... we would tackle and punch each other around a bit, but I wouldn't go out and focus on someone.

"This was the most serious," he told RNZ.

He also said that any other incidents were "not targeted" but would not disclose details.

Uffindell reiterated that when we was asked to leave King's College it was solely related to the assault he was involved in made on a 13-year-old student.

He said the incident was his fault and he takes full accountability.

"I try and live my life as an adult as a responsible person to set a good example to my children and to others."

The National Party leader Christopher Luxon and his deputy Nicola Willis only learned of Sam Uffindell's school teenage dormitory assault yesterday afternoon, it has been revealed.

Willis told RNZ said she found out about the incident just after lunchtime and she believed that Luxon also found out then.

She said Uffindell had disclosed the incident to the pre-selection panel, made up of local and national party representatives, and they had made the decision about not precluding him from standing for Parliament.

"That's a party matter. That's their judgement. Where I stand on this today is that I have advised Sam that what he should do now is be completely upfront with New Zealanders about this because ultimately it is the people of New Zealand and the people of Tauranga who will be the judges of us."

Willis described it as a serious incident and her thoughts were with the victim, saying it would have been a traumatic event at the time and something that would never leave you.

She said there should be room in Parliament for those who made serious errors, accounted for them but were now committed to using their position for good.

"If I thought that Sam was still the same man as he was when he was a 16-year-old when he committed this act then I don't think there would be a place for him in Parliament. However, I see that he is extremely sincere in his regret in his genuine apology and that he is being upfront about what occurred and that he is a different person today than when this happened."

His former school, King's College, has also spoken out after it was revealed the National MP assaulted a 13-year-old student while attending the school.

King's College headmaster Simon Lamb confirmed the incident and said it was dealt with at the time.

"The issue referred to in the Stuff article today was a matter which the College dealt with 22 years ago," said Lamb.

"Since that time, the College has not been involved in any follow-up activity with those involved, including the recent discussions reported in the article."

Sam Uffindell is the MP for Tauranga. Photo / File

The incident reportedly occurred in 1999 on the last night of term inside one of the King's College boarding houses.

It was reported by Stuff that the now MP for Tauranga apologised to his victim 22 years after the attack and nine months before he revealed his political aspirations.

Uffindell has detailed the late-night violent beating of a younger boy that led to him being asked to leave King's College while he was a student.

Speaking to Newstalk ZB's Heather du Plessis-Allan, Uffindell confirmed the incident and said it was "one of the dumbest, stupidest things I have ever done".

He also wouldn't rule out standing down as MP.

"It was one of the silliest, stupidest things I've ever done. I reall