A review into allegations of sexual assault by a Labour Party staffer has been unable to substantiate the claims, but did identify "overbearing and aggressive" behaviour.

New Labour Party president Claire Szabo said the report could not establish the most serious allegations, of sexual assault, nor other claims of sexual harassment.

"Some allegations that related to overbearing and aggressive conduct were found to be established, but were found to not meet the threshold of unlawful bullying," Szabo said.

"The respondent had accepted from the outset of the investigation that, at times, his conduct had been overbearing and aggressive."

Overall, the report concluded it could not find any misconduct that merited disciplinary action.

Prime Minister Jacinda Ardern told reporters that there should have been processes in place that meant this would not have been dealt with in the public domain.

"We have got to try get back to best practise," Ardern said, adding that "harm has been done to everyone involved".

It was time, Ardern said, to draw a "line in the sand" and start trying to look after our Labour members.

"We are not here to seek blame or malice," Ardern said.

She said the decision by former president Nigel Haworth to resign was an "honourable decision".

Labour needed to be a place where its members could raise concerns: "We can and must do better."

The only element of the report that would be made public was the executive summary.

"The full report will not be released," Ardern said.

She repeated a number of times at the press conference that "no one had been well served by this process".

'Discomfort and distress'

Szabo acknowledged "the discomfort and distress these matters have caused a number of our people, particularly the complainants, the respondent, and their families".

"I thank them for co-operating with the investigation. It is now time to get on with applying the lessons we have learned."

Labour president Nigel Haworth resigned during the saga in September, while the staffer at the centre of the claims - who strenuously denied the allegations - also stepped down.

Szabo said today that, despite the findings, it was clear the original inquiry process had failed.

Lawyer Maria Dew conducted the review of sex assault claims against a Labour Party staffer.

The new review was conducted by lawyer Maria Dew. She said there was not enough evidence to substantiate claims made by one complainant about an assault in February 2018.

"Her evidence was incorrect in several critical respects in relation to the events of that evening," the report says.

"The investigation also found that [she] and the respondent had been in a consensual personal relationship for some eight months by February 2018."

"There is evidence that she reported her allegation of assault and other distress about the relationship, to those close to her, in March 2018," Dew said.

"However, [her] recollection of material events about the evening in February 2018 was clearly incorrect."

Dew said the claims were also not consistent with Facebook messages the complainant had exchanged with the staffer.

The review also said the complainant had misled the investigation about an email sent to a senior party official, which it was previous alleged contained information about the February 2018 assault.

"The remainder of her evidence about reporting this allegation orally in her 9 March 2019 investigation committee interview is rejected as improbable when assessed against the weight of other witness evidence to the contrary," the report says.

The report makes two recommendations:

• That the accused staffer write a letter of apology to complainants impacted by his "overbearing and aggressive conduct" and that all parties receive an offer to a restorative meeting process
  • And that Young Labour members are provided with an annual induction process

The ex-staffer was the subject of an internal investigation from the Labour Party earlier this year following seven formal complaints about his behaviour.

That investigation cleared him of wrongdoing - but a review was ordered after the complainants said the process was unfair and sexual assault claims were ignored.

One of the complainants, a 19-year-old volunteer, claimed the staffer attacked her at a private residence in February last year.

She said she told Haworth and the three members of the party's investigating panel about what had happened.

Haworth and the panel disputed this, saying they were never told about a sexual assault claim.

The report released on Thursday does not cover Labour's handling of the process.

A separate report into those questions will not be released until next year.

The allegations are completely separate to an incident involving assaults at a Youth Labour camp.