"The Labour Party has some very serious questions to answer about what happened and how it handled the matter.
"While we don't know exactly what happened, I think the parents of the victims and the police should have been informed.
"What's important now is that they are appropriately supported and the matter is properly investigated."
Prime Minister Jacinda Ardern found out about the sexual misconduct only yesterday when asked about it as her post cabinet press conference.
She said this morning that she would have expected the parents of the young people to have been told.
Ardern addressed the summer camp on the night it opened before heading back to Auckland to meet Australian Foreign Minister Julie Bishop at a dinner hosted by Foreign Minister Winston Peters.
Ardern said she did not see any sign of misbehaviour while she was there.
The alleged assaults took place the next night at party.
Ardern told Newstalk ZB's Mike Hosking this morning: "The environment was not a safe one and that's something we have to fix.
"It shouldn't have happened, we should absolutely have made sure those people were looked after and that hasn't happened."
Apology to Ardern
Labour general secretary Andrew Kirton has apologised to her for the handling of the matter.
Kirton said he had apologised to Ardern for the handling of the matter.
Those affected had not been offered counselling until almost a month after the event.
"We could have brought the professional help in earlier, even though we were trying to be led by those involved.
"Also the delay with the communication after two of them got back in touch was not acceptable."
Kirton said he had not offered to stand down. Asked if it was acceptable given Labour's principled stance on sexual harassment issues, Kirton replied: "Well, we could have done better."
The allegations coincided with the ongoing #MeToo movement against sexual assault and claims of sexual misconduct at law firms in New Zealand, both of which Ardern was likely to be asked for comment on.
Kirton did not believe Ardern should have been told earlier – Ardern was not aware of it and was blindsided when asked during a press conference yesterday.
However, Kirton said Ardern would only have needed to be told for political reasons.
"She's characterised it as telling her it was a political management response and we were focused on doing the right thing for the young people, not on politics."
He said the risk was that the distress for those concerned would be magnified if the actions taken were higher.
Kirton said the parents were not told. Asked if he would like to be told if it was his children, he said he couldn't answer that because it had not happened.
"All I can do is take the advice of people that do deal with this all the time. But I totally understand that parents of people of that age would want to be told."
Minister knew about misconduct claims
Government minister Megan Woods knew about sexual misconduct claims at a Young Labour summer camp after one of the victims approached her.
Woods said she had received a Facebook message about the incident from a young person on March 4.
She "immediately" called Kirton to alert him and asked him to contact the person. She then let the young person know that a party official would be in touch.
"Two hours later she heard from the general secretary that he had been in touch with the young person and the situation was being handled appropriately."
A spokesman said she was aware of the nature of the behaviour involved because the person who contacted her had informed her it related to sexual misconduct.
Kirton said Young Labour representatives had emailed the four young people affected and two had responded.
A fortnight later one had contacted Woods via Facebook because they were unhappy there had been no reply to their email.
Woods said she had not spoken to other Cabinet ministers about it because she believed it was being dealt with by Kirton.
Woods is Minister for Energy and Resources and Christchurch Regeneration. She sits on the front bench.
Christine Ottaway, who managed the Waitawheta Camp, but has since retired, said they had very little involvement with the group and had not received any complaints.
"We just leave them to it."
Camp culprit 'deeply embarrassed'
Kirton says the 20-year-old alleged to have groped the four teenagers at the event was "deeply embarrassed" when confronted about it the next day.
"He was spoken to the morning after and my understanding is he was deeply embarrassed and they got him out straight away.
"My understanding from the conversation relayed back to me was that he recognised he had drunk too much and that he was embarrassed by what happened."
Kirton said the man was not a party member but was there with friends who were and was a supporter. He had also helped with transport for the event.
He has been banned from future events and from joining the Labour party.
Asked what Labour had done to try to ensure the young man did not repeat his behaviour in other company, Kirton said after dealing with those affected he contacted the man and offered the services of WellStop – an organisation for people who engage in inappropriate sexual behaviour.
He did not know if the man had taken that up. He was not aware of any complaints from previous Labour events.
Will police investigate?
Police Assistant Commissioner (Investigations) Richard Chambers said police did not need a complaint to be laid before it investigated.
"We reiterate our comment of yesterday that we encourage anyone with information they wish to discuss with police, or matters they wish to report, to contact us," he said in a statement.
"Our priority is to ensure that anyone who wishes to speak with us can feel comfortable in doing so.
"This means that we will not necessarily confirm specific details should further information become available to us about this matter."
Any decision to investigate would be based on the information available, which would be assessed to decide what further steps were required, Chambers said.
Criminal barrister Philip Hamlin said police generally wouldn't investigate sexual assault without a complaint.
Investigations should be thought of as a fact-finding mission, he said.
Police do not necessarily accurately know the exact nature of an alleged assault through second or third-hand information.
"You really want to know first-hand what the complainant says happened to him or her.
"It's quite a critical step quite early in the procedure to try and get their facts straight."
After hearing from those who had experience of any incidents first-hand, police would then speak to witnesses and others to try and verify those facts.
A complaint did not have to come from a victim for police to investigate, but victims were not obliged to talk to police about their own assault, Hamlin said.
However, usually police would want the victim to cooperate.