At least three staff who worked for Labour MP Gaurav Sharma claim they raised concerns about him after quitting during his first year as a Labour MP - which allegedly led to a staffing freeze that sparked Sharma's public outburst against the party last week.

But Sharma has now received support from his Hamilton West electorate committee in a letter to Labour's caucus and hierarchy in which they describe the MP as "incredibly conscientious" and who has their full support.

The letter, obtained by the Herald, urges the party to independently investigate his claims.

The saga has entered the fifth day, following Sharma's explosive column on nzherald.co.nz last Thursday, in which he blindsided the Labour Party with claims that bullying was rampant in Parliament, and that he had been subjected himself to bullying from another MP.

In her round of media calls this morning, Prime Minister Jacinda Ardern rejected Sharma's claims, saying they had arisen as a result of staff concerns about his own management style.

Sharma told the Herald yesterday he had repeatedly said that if staff had complained about him, Parliamentary Service should investigate him but they had not done so, despite his wish to clear his name.

Sharma said Parliamentary Service and Labour's former whip Kieran McAnulty had also refused to investigate his own claims that one staffer was "incompetent" and not up to the job – and his claims that McAnulty had bullied him while dealing with Sharma's staffing issues.

"Why wouldn't they investigate me as I have repeatedly asked? Even their letter in May said they won't investigate me to clear my name. I have repeatedly said that if there are any claims [by] any staff, please investigate it. I have been the only one who has been asking for an investigation [into] both sides, but they have refused it."

He said some of the claims against him were "beyond ridiculous, some are even fabricated" and evidence in his favour from another staffer had been ignored.

Parliamentary Service chief executive Rafael Gonzalez-Montero has now also responded to an allegation by Sharma that an MP and their staffer misspent Parliamentary funding – but that Parliamentary Service had not looked into it and had instead alerted the Labour whips' office of his complaint.

Gonzalez-Montero told the NZ Herald that was raised last year and he had looked into it and considered the spending was for parliamentary business and within the rules.

"It related to a Wellington-based staff member travelling to a member's electorate office for the purpose of team building and assisting the wider team. This is normal practice for many members when establishing a new team which has staff dispersed in different regions."

However, Sharma told RNZ "they [Parliamentary Service] definitely did not investigate it". He alleged the misspending was "hushed".

He also questioned why the Parliamentary Service informed the Labour Party about his complaint. Sharma claimed he was bullied as a direct result.

Electorate committee letter

In a new development, Sharma's Hamilton West electorate committee has written to the Labour Party and Labour's caucus in support of Sharma and calling for an independent investigation into the claims he had made.

"Given the serious concerns he has been raising for a long time, we hope [there is] an independent and in-depth inquiry into his claims and give him the fair trial he deserves," says the letter.

The letter, with more than 20 signatures, said Sharma would continue to have their "unconditional support" until any such inquiry reported back.

Labour Party general secretary Rob Salmond said they had received the letter but would not comment on whether the party intended to investigate the claims Sharma had made – or whether it was considering invoking disciplinary proceedings against Sharma himself. Labour's rules include disciplinary procedures against those who "bring the party into disrepute".

The signed letter of support for Dr Gaurav Sharma from the Hamilton West Labour Party.

One of Sharma's former staffers told the NZ Herald last week they had to go for counselling after working in Sharma's Hamilton West office, describing him as "controlling" and the job as "like walking on eggshells".

Sharma had responded by saying his own complaints about a staffer's competence was not taken seriously or investigated.

Sharma said the hiring freeze on him was only lifted on Thursday, following a meeting to which he had taken his lawyer. That afternoon, he had sent the opinion piece on the issue to the NZ Herald, alleging bullying against him by MPs and Parliamentary Service.

On Friday night, he also wrote a lengthy Facebook post in which he hit out at Labour and Parliamentary Service for "bullying", expressing particularly strong opinions about former whip Kieran McAnulty for his handling of Sharma in relation to his office staffing.

McAnulty has not responded to requests for comment. However, last week, Labour leader Jacinda Ardern rejected Sharma's allegations about bullying but confirmed the party whips had been dealing with him over employment issues. She said that had included the freeze on hiring while they put in place coaching and mentoring.

"I was aware that ... those interventions weren't necessarily welcome."

PM responds to latest Sharma claims

Asked if there was a bullying problem within the Labour Party, Prime Minister Jacinda Ardern told TVNZ today: "Uh, no."

"In fact, the issues that (MP) Gaurav Sharma has raised have come about as the result of the fact that - as I said last week - we've been aware that there have been employment issues in his staff, in his office," Ardern told Breakfast.

"So staff members raising concerns about his management and you've seen that some of that subsequently has played out publicly."

She said they had an obligation to make sure all staff members were safe and well looked after; which had then seen interventions happen.

Ardern said Sharma had not always agreed with those interventions and that had then given rise to his complaints.

Put to her about detailed bullying allegations and claims of the misappropriation of parliamentary funding, Ardern said the claim that he made to Parliamentary Services was rejected.

"I have looked at this issue - although he never raised it with me directly and the first that I saw some of these issues raised by him was in the Herald."

She said constructive interventions and attempts to improve his office, which he did not always agree with, dd not constitute bullying.

Ardern told the AM Show today that Sharma only raised issues after staff raised concerns with his management within his office and interventions were made by the whips of parliamentary service which he disagreed with.

"That is actually the very reason that this has occurred in the first place... we do make sure we have a good working environment for everyone here in parliament."

Ardern couldn't answer how many Labour MPs were under bullying reviews saying with 237 staff she wouldn't necessarily be familiar if there is an issue raised.

"I however am very clear on that we have to have processes that make sure that protect and work through issues that staff members raise, should they raise them," she said.

Ardern said the allegations about misuse of taxpayer money were taken "very seriously" and in this case were found to be unsubstantiated which meant it was not an issue.

"The issue was that (Sharma) believed a staff member had travelled inappropriately with a MP so he raised that with parliamentary services who are in charge of making sure the rules are followed, they found it was not inappropriate."

"With issues such as this we will always look to refine our processes, we will always look to reflect on the way we are conducting ourselves because we do have to be to the highest standard," Ardern said.

When asked if Ardern was going to stand down MPs in question while a review is carried out, just as National did with Sam Uffindell, she said: "no".

Ardern said she had gone through the documentation that existed around these accusations. "At no point did Gaurav raise these directly with me, even though I'm the leader of the Labour Party."

Last week, Ardern indicated she was not comfortable with the way Sharma had gone public with his issue.

"Clearly, there are a number of issues here at play and that would be one of my primary concerns ... because it relates to other staff members, it does really raise a number of concerns."

Parliament is in recess this week so Labour's caucus will not meet again until next Tuesday.