A man at the centre of sexual assault allegations at a Labour Party summer youth camp has been charged.

Police said a man, 20, has been arrested and bailed to appear in court on four charges of indecent assault.

"This follows an investigation into allegations relating to a Labour Party summer camp at Waihi," police said.

The man is due to appear in the Auckland District Court on July 5.

Labour Party president Nigel Haworth said: "The Labour Party backs the decision of the police to lay charges against an individual relating to allegations of indecent assault at the Young Labour summer camp earlier this year.

"The party's internal report, prepared by Maria Austen [formerly Berryman], is focused on the party's policies and procedures around the summer camp, if they were properly applied, and how we should correct any deficiencies.

"Maria Austen's investigation is ongoing and separate from the police actions today. We will report back on her findings once we have received and considered them."

Neither Labour's deputy leader Kelvin Davis nor senior MP Grant Robertson would comment on the arrest or wider issues around the handling of the camp, saying it was now before the courts.

Davis rejected any suggestion the arrest and the looming report by lawyer Maria Austen had anything to do with the timing of Labour General Secretary Andrew Kirton's move to leave his role for a new job with Air New Zealand.

Davis said that was "entirely coincidental".

"My understanding is it's just one of those things. He resigned last week, he's got a new opportunity and this has come out."

He said they had not been given any updates on the review by Austen and her report was due within the next few weeks.

National Party leader Simon Bridges also declined to comment because it was before the courts.

The Labour Party was under fire in March when details emerged of the February camp and allegations of assaults of four young people, all believed to be just 16, became public.

The alleged assaults took place at an evening event and there were reports of heavy drinking, even though some were too young to consume alcohol.

Earlier that day Prime Minister Jacinda Ardern had spoken to the group.

Kirton has previously apologised for his handling of the aftermath of the summer camp scandal.

Labour's hierarchy had failed to tell Ardern about the scandal and there were complaints about the handling and the failure to refer the issue to police at the time.