Bullying claims by NZ Labour MP Sharma

Both sides of New Zealand politics stand accused of cultural failings after revelations of violence and allegations of bullying in parliament.

The week in Wellington has been dominated by reports of historical assault and abuse by newly elected opposition National MP Sam Uffindell.

But on Friday, Prime Minister Jacinda Ardern was forced to defend her party's management of its own MPs after one went rogue.

Gaurav Sharma, the first-term member for Hamilton West, wrote a savage opinion piece in the NZ Herald alleging MPs are "rampantly" bullied by other members and their parties.

"The abysmal culture of our political parties ... continue to betray the trust of our voters," he wrote.

"I am sure the list of similar stories with no support for MPs being bullied and no consequences for MPs bullying their colleagues would easily fill a book or two."

Without attacking specific members or individuals, Mr Sharma aimed a broadside at the leadership of Parliamentary Services, which provides staffing and support to MPs and parliament.

In a pointed reference to Ms Ardern's leadership style, Mr Sharma said, "politicians especially at the top of our current system and from parties across the political spectrum often talk about 'changing the system' and 'kindness' but as the saying goes 'charity must start at home'."

Mr Sharma went against protocol by not running his article past party chiefs prior to publication.

Ms Ardern disputed the allegations, saying she was "immensely proud" of her team and had "never worked with a team that's better".

She said Parliamentary Services had slapped a hiring pause on Mr Sharma, suggesting his staff had raised issues of their own.

"The focus of this was to ensure coaching and mentoring was constructive ... and making sure our MPs are the best employers possible," she said.

"I'm confident Labour whips alongside the Parliamentary Service have done their job appropriately. My primary concern at the moment is Gaurav's wellbeing."

Mr Sharma has gone to ground since the claims, telling the Herald "I am not the bully" and "we'll find out" who they are.

Bullying claims in parliament are not new.

In 2018, Speaker Trevor Mallard commissioned Debbie Francis to conduct an independent inquiry into workplace issues.

The report's findings were disturbing, beginning with the opening line, "bullying and harassment are systemic in the parliamentary workplace".

In a survey of 1000 staff, a majority said they had observed or experienced unreasonable or aggressive intimidatory behaviour (78 per cent), destructive gossip (69 per cent), or demeaning language and gestures (66 per cent).

Mr Sharma's claims come after a week centred on the behaviour of Mr Uffindell.

On Monday, it was revealed the newly elected Tauranga MP was expelled from a prestigious boarding school - 23 years prior to entering parliament - for a nasty assault.

As a 16-year-old, Mr Uffindell bashed a 13-year-old in a dorm at Auckland's King's College, leaving it until last year to apologise.

The victim accepted the apology until he saw Mr Uffindell start a political career, when he "felt sick" according to news outlet Stuff.

National leader Chris Luxon initially backed the MP as a "changed man".

On Wednesday, Mr Luxon stood Mr Uffindell down from the party's caucus and ordered an independent investigation when new allegations surfaced of abusive and unsavoury behaviour at university.