Tauranga MP Sam Uffindell has made a statement apologising for his reported involvement on an attack against a young student at King's College when he was aged 16.

'When I was in fifth form (year 11), I and some other students in my year went into another dorm at the boarding house at the end of term and I punched a younger student in the arm and body multiple times," says Uffindell.

"We were subsequently asked to leave the school."

In a statement to SunLive, Uffindell says he has reflected on this incident multiple times over the 20 years since it occurred, and has "no recollection of using anything other than my fists".

"Nevertheless, it's one of the stupidest things I've ever done and something I deeply regret. I've worked hard to be a better person than I was as a teenager and to be a good role model to my children.

"After I came back to New Zealand I called the person and apologised for the harm I'd caused. We had a long conversation and I was grateful that he accepted my apology. My apology was genuine then, and it is genuine now.”

The National Party's newest MP was asked to leave his exclusive boarding school after viciously beating a younger student late at night, reports Stuff.

Uffindell offered the man an apology last year, 22 years after the attack, and nine months before he publicly announced his political aspirations.

He says the timing of his decision to say sorry is not linked to his decision to begin a career in politics, but that the incident had been 'nagging” at him, and he wanted to atone.

'It was one of the silliest, stupidest things I've ever done. I really regretted it, I do really regret it still,” says Uffindell.

The victim, who was 13 years old at the time, was left with severe bruising and significant trauma.

Police were not involved.

Instead, Uffindell was disciplined alongside three other teenagers who joined in on the beating, and asked to leave the school, Auckland's King's College.

Uffindell was in Year 11, or fifth form, and aged 16 years old when he attacked the younger boy.

He went on to finish his schooling at St Paul's Collegiate in Hamilton.

Uffindell entered Parliament this year after winning the Tauranga by-election in June.

A National spokesperson says the party was proactively informed about the incident by Uffindell during the candidate selection process.

They says it was a significant event reflecting a serious error of judgement by a then 16-year-old, for which he had since apologised, and regretted to this day.

Prime Minister Jacinda Ardern told media soon after the news emerged, any decision on Uffindell's suitability as MP and his future at Parliament would be up to National leader Christopher Luxon.

The victim, who Stuff has agreed not to name due to privacy concerns for his young family, says Uffindell contacted him out-of-the-blue through a mutual acquaintance in July last year.

Uffindell wanted to apologise, which after some consideration, the victim agreed to. At the time, he says he would never forgive the boy who hurt him, but forgave the man Uffindell had become.

'But then a few months later I sat down to watch the news on the couch with a beer and there he was, running for Parliament,” the victim says. 'I felt sick.”

National Party leader Christopher Luxon at Tauranga candidate Sam Uffindell's election night headquarters. Photo: Mark Taylor/Stuff.

Uffindell hadn't mentioned his political intentions during the apology, the victim says.

'At the time, he says not a day had gone by when he didn't think about it. He used his family, saying he has daughters and would be sickened if anything happened to them,” he says.

'I believed him. But seeing that - it made me feel his apology wasn't genuine, he was just doing it to get his skeletons out of the closet, so he could have a political career.”

The man says the original incident happened on the last night of term in 1999, inside one of the King's College boarding houses.

He had been in bed in his dorm room after lights out, when four older boys came in and jumped on him and began beating him, he says. He thought the boys had been using wooden bed legs unscrewed from their dorm.

'I was covering my head … they were smashing me,” he says. 'I don't remember much but when it was over everyone ran into the next dorm and lay down on the floor between the beds there to hide.”

The victim says later on, there were photos taken of his injuries. 'They show this skinny little white kid covered in bruises,” he says. His ribs weren't cracked, but there was some damage to the cartilage.

The victim's older brother - who was in the next-door dorm - remembers the whole dorm of third formers rushing in, causing mass confusion in the dark.

'We thought it was a pillow fight, an end-of-term tradition type thing,” the brother says. 'But it wasn't, these boys were lying down saying ‘they've beat him up, they've beat him up'.”

Eventually, he found out that the boy who'd been attacked was his younger brother. He grabbed a cricket bat and went looking for the offenders in a rage, he says. Before he could find them, the housemaster stopped him, took him to his office, and calmed him down.

'The housemaster told me he would take care of it and sent me back to sleep,” the brother says.

Stuff talked to three other witnesses who say they were present at the time.

UUffindell ran on a platform advocating better infrastructure and tougher anti-gang laws. Photo: Supplied/Stuff.

Afterwards, two of the perpetrators - Uffindell and another boy - were either expelled or 'asked to leave” the school. Two others were suspended for two weeks at the beginning of the next year.

Sam Uffindell says he told the National Party about the incident that saw him "asked to leave" King's College.

Uffindell does not mention King's College in his biography online.

The bullying incident was not disclosed to voters during Uffindell's successful candidacy in this year's Tauranga by-election.

Uffindell won the seat with a comfortable majority, after it was left open by former National Party leader Simon Bridges' resignation.

He gave his maiden speech to Parliament last week, speaking at length about how Tauranga was beset by gang issues and a 'growing culture of lawlessness, lack of accountability, a sense of impunity, and significant underlying generational social problems”.

'We need friends, family, and, in particular, parents, to step up and show what is right,” he says.

The victim says he probably wouldn't have agreed to speak to Stuff about the incident if Uffindell had properly handled the apology.

'If he really cared he would have at least given me a heads-up that he was planning to enter politics,” he says.

Uffindell is expected to discuss his future with National Party members in Wellington today.

- Additional reporting by Stuff.co.nz/Kirsty Johnson.