Young Labour supporters were drinking excessive amounts of alcohol "to get absolutely hammered" on the night a man is accused of sexually assaulting four people at the political party's summer camp, a court has heard.

A 21-year-old man is on trial in the Auckland District Court this week, accused of indecently assaulting four people - two men and two women - at the Labour Party summer camp near Waihi in February 2018.

The accused, who has name suppression until at least the end of the trial, is charged with five counts of indecent assault.

He allegedly grabbed and squeezed a man's testicles, touched another man's genitals twice, kissed a woman on her neck and face and groped a second woman's breast and bottom.

Today, the jury heard from the second male complainant.

He said there was a party atmosphere at the Coromandel Peninsula campground the night of the allegations.

There was "excessive amounts of alcohol", he said, while people were "not drinking for enjoyment but drinking to get absolutely hammered".

Dancing Queen by ABBA and Toto's Africa were blaring, he said.

"Classic [party] music, it wasn't church music or anything like that," he said.

The accused, he also recalled, was "on top of a table dancing with his shirt off".

• Labour Party camp trial: 21yo accused of indecent assault

"He ripped his shirt off, I believe it was a singlet actually."

Several of the teenagers and young adults were also taking photos underneath a banner with the Labour Party's "let's do this" election campaign slogan on it.

It was there that he alleges the accused first groped his genitals.

"I knew he was incredibly intoxicated at that point," the second complainant said.

He told the court he pushed the accused away.

"I just thought this guy's drunk and being a bit of an idiot."

But there was a second incident, where the accused allegedly grabbed his genitals again.

"Don't, go away," the second complainant said he told the accused.

"At that point I think he got the message."

But the complainant recalled also "laughing about it at the time".

"Both instances were extremely bizarre ... It just felt weird.

"I'd be the first to admit that this type of incident is low scale offending."

The accused's lawyer Emma Priest has told the jury her client was "a young man at a party caught up in a political storm".

The allegations by the second complainant, Priest said, simply didn't happen.

She said her client "did something completely different which was meant as a joke".

"There may have been some drunken antics as you might expect at a party but there is no criminal offending at all," Priest said.

Maria Austen, a Wellington lawyer, conducted an external review of Labour Party procedures after the allegations were made.

Austen's report included several recommendations, however, Prime Minister Jacinda Ardern has said the report will not be publicly released while the court proceedings were ongoing.

Ardern spoke to those at the camp the day before the allegations.

The trial is expected to conclude at the end of the week.