Labour MP Gaurav Sharma has been suspended from caucus effective immediately, Prime Minister Jacinda Ardern has announced.

It is the "most appropriate" response to "repeated breaches of trust" committed by the MP, Ardern said after a special party caucus meeting today.

Sharma, who did not attend the meeting, was phoned, texted and emailed to join today's meeting but did not join, Ardern said.

Today's press conference was delayed from 4pm to 4:30pm so Sharma could be contacted ahead of the decision.

Ardern said she called and texted, but did not reach him, adding she hoped this wasn't the first time he was being informed.

Sharma will continue as MP for Hamilton West but not take part in caucus decisions unless invited.

The sense of trust has been broken amongst caucus, Ardern said.

Ardern said a review will take place in September to see whether Sharma could return to caucus.

The decision to suspend the MP was "unanimous".

Caucus retained the ability to revisit Sharma's status within caucus at any time.

Offers of coaching, mentoring and temproary staff were made to Sharma throuughout the last 18 months

All were not appreciated by Sharma, Ardern said.

Ardern said had those interventions not been made, Ardern said she feared there would have been different allegations made, including negligence.

She had nothing to substantiate the claims made by Sharma, which included bullying.

The concerns of staff had been "obscured" in recent days, Ardern felt, but they were her primary concern.

Caucus has initiated a mediation process for these issues to be resolved between Sharma and the whips.

The mediation was an opportunity for Sharma to litigate his concerns without compromising confidentiality of staff.

Ardern said it was "frustrating" and "disappointing".

She didn't want MPs talking about themselves given the issues facing NZ now.

MPs are "very hurt and upset" at what had happened, Ardern said.

She defined it as serious misconduct.

The door had been left opened for Sharma to come back in as an active caucus member because he was part of a team, Ardern said.

Ardern said last night's secret meeting was not a "formal" meeting as not all members were there, adding the result was not "predetermined" as Sharma had claimed today.

"That would not be a fair process," Ardern said.

A small number of MPs were absent from the meeting last night, meaning it wasn't a full caucus meeting.

It was a forum for issues and concerns to be raised.

Asked about Sharma's allegations, Ardern said part of Labour's process was to have a meeting for Sharma to voice his concerns.

Today's meeting time was suggested by Sharma but he still did not participate, Ardern said.

Asked whether he had gone rogue, Ardern said she couldn't say that given she hadn't spoken to him.

It was of note to Ardern that there was only one person who was unable to make today's meeting.

Ardern couldn't say whether Sharma was aware of the meeting taking place last night.

The reason that meeting was held because Labour MPs didn't feel they had a safe space to share their thoughts with Sharma there.

Someone sent a screenshot of the planning of today's caucus meeting, which also had evidence of the late night secret meeting, to Sharma, Ardern said.

She said she was "somewhat embarrassed" by the incident.

She would not show sympathy for Sharma, instead sympathising with Labour MPs that didn't feel comfortable speaking in front of him.

Ardern would not confirm who it was that sent Sharma a screenshot that accidentally included evidence of last night's meeting taking place, which alerted Sharma to its existence.

Earlier it was revealed Labour MPs had a secret Zoom meeting last night - without Dr Sharma.

The NZ Herald understands MPs met at 8pm, but Sharma says he was not told of the meeting.

He found out about it after a message - including a photo of Kelvin Davis on the zoom call - was sent to him by mistake.

"Apparently caucus had a full meeting at 8pm yesterday with all members except me and the decision was predetermined," Sharma said in a text message sent to NZME.

The Herald has confirmed last night's meeting from other sources.

The meeting was organised by a Signal group and the whips started to organise it on Monday morning to get a suitable time - before Sharma had put up a further Facebook post on Monday afternoon.

Ardern did not mention any plans for a meeting set for last night.

MP for Hamilton West Dr Gaurav Sharma (back row, centre) seen here with his Labour colleagues on the steps of Parliament in 2020. Photo / Mark Mitchell

Sharma today told the Herald he was unsure whether he would make today's afternoon meeting, given he had other engagements.

However, he expressed his desire to have a "fair trial".

The Hamilton West MP, who went public with allegations of "rampant" bullying within Parliament last week in a Herald column, has also claimed some MPs - including some in the Labour Party - have sent him supporting messages and are grateful he has spoken out.

Sharma told the Herald that if he was expelled from the party, he might stay on as an independent MP.

"I'll try my best to make it [the meeting] but as I said, I'm just trying to squeeze everything in."

Sharma said he had been given "very short notice" of the meeting, claiming he was told by current senior whip Duncan Webb between 5-6pm yesterday that the meeting would be held today.

He understood there was only "one point on the agenda" - Sharma's allegations and how they were discussed publicly.

- Adam Pearse and Claire Trevett, NZ Herald