National Party leader Christopher Luxon on whether he trusts Sam Uffindell after latest allegations: 'I have up until last night'

National leader Christopher Luxon admits his trust in the party's newest MP Sam Uffindell is shaken after more allegations of bullying emerged against him.

Tauranga MP Uffindell was on Tuesday night stood down pending an investigation into fresh allegations of bullying behaviour in his university years. 

A former flatmate of Uffindell, who lived with him in 2003, told RNZ he was a bully and, on one occasion, he "smashed" on a door and yelled obscenities - telling her to "hit the road fatty" before she decided to flee and climb out of her window. Uffindell has rejected the latest bullying accusations.

"I feared for my safety, I was scared," she said.

The woman, who wished to remain anonymous, also claimed Uffindell was involved in the "excessive" use of alcohol and drugs.

Her father, also appearing on RNZ's Morning Report, said Uffindell needed to take responsibility for his actions.

"It was clear at the time he had real issues, real problems with this - he was out of control and I really think he needs to front up, take responsibility."

Uffindell on Tuesday night released a statement responding to the allegations.

"When I was a student at Otago I enjoyed a student lifestyle, which included drinking and, at times, smoking marijuana. While in second year a number of flatmates fell out - and two of the flatmates left midway through the year," Uffindell said.

"I reject any accusation that I engaged in behaviour that was intimidatory or bullying."

The latest allegations followed revelations earlier this week that, as a 16-year-old, he violently assaulted another boy while attending Auckland's King's College.

When Luxon was asked if he still trusts the MP, he told AM the new information was impossible to ignore.

"I have up until last night," Luxon said of whether he trusted Uffindell. "I guess the reality of new allegations coming in that we were unaware of - that do need to be taken really seriously - is why I think an independent investigator with a very clear focus... to take these allegations serious is important."

Luxon said the party relied on candidates declaring as much of their past as possible.

"Essentially what's happened is, I was informed and reassured that King's incident was the most serious... but we've subsequently had new allegations and it's only appropriate that I only take pretty swift, quick action.

"These are new allegations and they are serious and they are concerning, and they need to be taken very seriously and that's why I have to go through an independent process to determine those findings - then we'll make a decision after that."

Luxon went on to say there have been no further allegations made against Uffindell, other than those already reported.

He would not say what action he'd take should the investigation substantiate the allegations.

"I'm really not going to get into that right now," Luxon told AM host Ryan Bridge. "What I really want is an independent investigator who's highly respected to hear both sides of that story - I owe that to the alleged victim.

"Equally, I also owe it to Sam given his dispute of those events and, until I get those findings, I can't speculate on that." 

Luxon also wouldn't get into whether another Tauranga by-election being triggered was on the table.

"I understand the question but the reality is, until I get those findings from that independent investigation, I'm not prepared to talk further about that," he said. 

It's not the first time the National Party's selection process has been scrutinised in recent years. It came under fire following multiple high-profile departures of MPs including Hamish Walker, who leaked COVID-19 patient details to the media, and Andrew Falloon, who sent unsolicited sexually explicit images to young women.

Candidate Jake Bezzant also left the party last year after serious allegations emerged from an ex-girlfriend.