Young Labour events will only resume if safety can be guaranteed, and a senior member of the party will have to be present.
The party review, led by Wellington lawyer Maria Berryman working alongside the Sexual Abuse Prevention Network, would look into party procedures with a view of ensuring safety at future party events.
Ardern said the review would also look at the Waihi incident, including whether the parental consent forms mentioned underage drinking, and if there was any drug use.
"There were parental consent forms that obviously did not protect those young people, nor their parents. That is why Young Labour will not be running those camps anymore."
Ardern said she "cannot hand on heart rule out that this hasn't happened before", and the review would also hear any historic claims of sexually inappropriate behaviour at party events.
She said the party had acted "very, very badly" over the Waihi incident, but denied the party had tried to sweep the matter under the carpet. The measures announced today showed that the party was taking ownership of the matter.
Ardern put the blame squarely on the party and not on anyone in particular, such as Young Labour or Labour MP Liz Craig, who was photographed at the camp with young people who appeared to be drinking on the night in question.
Craig told the Herald that she had stayed overnight at the camp due to regional flight schedules.
"I went to bed early and then left early in the morning to get to the airport. Thus was not aware of the issues being discussed in the media until now," Craig said.
Haworth said he had no intention of resigning, saying it was his job now to ensure that party events will be held in safe environments.
He also defended party general secretary Andrew Kirton, while also acknowledging that Kirton could have handled the situation better.
Ardern said she would like to speak to the victims but would now have to wait until the police investigation was completed.
The party has been criticised for how it followed up the concerns of the victims, one of whom contacted Cabinet Minister Megan Woods after becoming frustrated with the lack of communication.
It has also faced questions over why it did not immediately inform the victims' parents, police, or Ardern, and why it took three weeks to seek advice from a sexual assault prevention agency.
Ardern said the party had failed the people at the camp.
"We failed the young people who told us they had been hurt – this failure left them feeling abandoned and I am deeply sorry for that. It's not good enough. We let them down."
Haworth said the party had failed in its duty of care.
"We want to apologise deeply to the four young people who have been grievously treated, and to their families who are obviously facing issues on this front, and also to the other young people who took part in the camp.
"We apologise and we are really, really upset about this."
A second allegation has emerged, which took place at another party event. The party has offered support for the victim, a woman, including support if she wanted to lay a police complaint.
