Labour Party minister Megan Woods was made aware of the alleged sexual assault of four people at a Young Labour summer camp by one of the victims.

It is alleged a 20-year-old man sexually assaulted four teenagers, all aged 16, including putting his hands down the pants of at least three of them.

There was alcohol present at the camp, despite some of the attendees being underage.

HAGEN HOPKINS/GETTY IMAGES Megan Woods saw a Facebook message about the alleged incident from a young person on March 4, a spokesperson said.

The Young Labour supporter was ejected the morning after the alleged incidents took place, and barred from future events.

READ MORE: Labour Party confirms sexual misconduct at camp - parents and police not told

The alleged incidents took place on February 10, and Labour Party President Nigel Howarth, Senior Vice President Beth Houston, and General Secretary Andrew Kirton were made aware.

MONIQUE FORD/STUFF Jacinda Ardern says the Labour Party dropped the ball in its handling of alleged sexual assaults at a Young Labour summer camp last month.

Kirton said the party did not tell police, the victims' parents, the prime minister, or other senior Labour Party MPs in order to keep the circle small, and not risk further distress to the victims.

However, Tim Murphy, the co-founder of the news site Newsroom, which broke the story, told RNZ one of the victims was dissatisfied with the way the incidents were handled and got in touch with a senior Labour MP, inside Cabinet, to share their concerns.

Murphy said the victim was frustrated at the lack of contact, and follow-up support, from Labour.

A spokesman for Woods said the minister saw a Facebook message about the alleged incident from a young person on March 4.

She immediately called Kirton and alerted him and asked him to contact the person.

She then let the young person know that a party official would be in touch.

KEVIN STENT/STUFF Labour general secretary Andrew Kirton has informed the Prime Minister's office of a second sexual assault alleged to have happened at a Labour Party event in the last decade.

Two hours later Kirton told Woods he had been in touch with the young person and the situation was "being handled appropriately".

The spokesman said the minister was not aware if the young person who messaged Woods was a victim. However, Newsroom's Murphy said they were.

Meanwhile, Prime Minister Jacinda Ardern was not made aware of the alleged incident, and found out through the media on Monday.

Ardern acknowledged Kirton dropped the ball in terms of the delay in seeking professional support for those involved.

The party was made aware of the alleged incidents after the event, and checked in with the victims. But it wasn't until about a month later that professional support services and counselling were offered to those involved.

The follow-up took too long, Ardern told RNZ, adding that Kirton would keep his job, but he should have sought professional advice and support sooner.

"Of course we have to do better. We know we have to do better," she said.

Ardern said she would investigate how the alleged incident was handled by the party, and about the presence of alcohol.

While the camp organisers did not provide alcohol, it was brought to the event by the attendees.

The attendees, some of whom were underage, should never have been around alcohol, she said.

"The responsibility does sit with us. These are young people ... We clearly needed to make sure it's a much safer environment than it was."

Labour had also received criticism for not alerting police, or the victims' families.

But on Monday, Kirton said he stood by his decision to limit the number of people who were made aware of the alleged incidents.

Kirton said the party handled the situation with a "victim-led" focus on the back of advice from a Wellington sexual violence charity.

However, it was now clear that advice was not given until about a month after the alleged assaults took place.

Labour said the victims were asked on more than one occasion what support or follow-up they would like, or required, and at no point did they ask for police, or their families to be told.

Kirton said he wasn't aware of any of the victims taking their complaint to the police, although both he and Haworth had offered their support to the victims if they chose to do so.

Kirton told RNZ he wouldn't be offering his resignation over the alleged incidents.

He said it was decided it would be appropriate for the young people themselves to go to police, if they chose to.

Meanwhile, the parents of the victims hadn't been told about the alleged incident because "we wanted to deal with the young people in the first instance," he said.

Ardern told RNZ if she were a parent of one of the victims, she would want to know. However, the party had acted on advice provided by experts.

It is understood the alleged offender has also been offered counselling and support.

WHERE TO GET HELP

Rape Crisis - 0800 88 33 00 (24hr service), click link for information on local helplines

Victim Support - 0800 842 846 (24hr service)

The Harbour, online support and information for people affected by sexual abuse

Women's Refuge (Females only) - crisis line available on 0800 733 843

Male Survivors of Sexual Abuse Trust (Males only), Helplines across NZ, click to find out more

If you are in danger, or are being subjected to sexual violence, call 111.

* Audio courtesy of RNZ