A teenage girl laid a rape complaint with police two years ago after an incident with three men in the Roast Busters group, police have confirmed.

The Roast Busters are a group of Auckland men, understood to be aged 17 and 18, who allegedly had group sex with drunk teenage girls and bragged about it online.

Police confirmed a 3News report tonight about a complaint being made at the time of the alleged rape - in December 2011 - when the girl was 13 years old, but that no charges were laid.

The girl told 3News she believed she was one of the group's first victims.

Police had said there was no evidence to proceed with her complaint, she told 3News tonight . Police confirmed this was the case in a statement following the news report.

They said the complaint was " thoroughly investigated".

"Whilst this was a distressing situation for the girl and her family, police determined that there was not sufficient evidence to bring a prosecution," they said.

The alleged victim told 3News that during the incident she was alone in a room with three men. One of them stood to her left and and one to her right, and another "hopped" on her.

"I was asking ... to hop off me. I was scared and stuff," she said.

"It was pretty terrifying. I was more traumatised by the fact I was 13 and losing my virginity."

She added that the alleged rape stopped after one of the men put a stop to it.

The girl said she was traumatised during an interview with police and had been asked to "act out" what had happened with dolls.

She also alleged that police asked her what she had been wearing and had said that she was wearing clothing "that were pretty much asking for it".

"I can't believe nothing was done because from then on I've had friends who have been sexually abused by them," she said.

"I've seen posts by friends on Facebook saying the Roast Busters ruined their lives.

"If something was done, it would have never happened ... they've gotten away with so much."

Police said that out of respect for the victim and her family they could not discuss specific details any further.

"The victim's complaint is still part of the continuing investigation and should new supporting evidence come to light as part of the ongoing enquiry , the decision in this case not to prosecute will be reviewed," police said.

Police met the girl’s family this morning and "re-stated their absolute commitment to doing their best by their daughter.

"Inappropriate and offensive comments that are alleged to have been made to the victim in this case by police are under investigation."

The girl also said that one of the alleged Roast Busters had written an apology to her over Facebook, saying she was "100% right".

Earlier, the Roast Busters were publicly defended by an unlikely source - their female friends.

The young women say the girls involved with the Roast Busters knew exactly what they were getting into. Many of the girls had group sex with the gang more than once, showing that they were willing participants, the friends claim.

Leilani Hargreaves, 18, says she has known Roast Busters ringleaders Beraiah Hales, 17, and Joseph Parker, 18, since they were children and describes herself as a close friend.

"It was all a joke to start with, but it escalated into a lot more when the girls started wanting it. Everyone knew about them, they all knew exactly what they did yet they still hung out with them," Hargreaves said.

Hargreaves and four of her friends appeared on TV3 last night, speaking out on behalf of the group. They said Hales and Parker were "not rapists" but "cool dudes", and that drunken group sex was actually "normal in West Auckland".

"Not for everybody though it's just the young ones - 13 to 15-year-olds - that's what they do", one of the girls claimed.

Hales' and Parkers' friends have also taken to social media to defend them, posting that the girls "knew what would happen" and that "the girls that did it gave them consent and even went back for more!"

Some of the girls in the Roast Busters circle used online handles such as "slutstation" and answered explicit questions about their sex life online.

One claimed that the way she usually started a conversation was, "wana roast".

At least one girl, however, has said she didn't consent, telling TV3 that she was underage and so drunk she was "blacking out" when three of the Roast Busters had sex with her.

But police say none of the girls and women involved have been willing to file a complaint.

Waitemata police district commander Superintendent Bill Searle said police still needed admissions, complaints, or other evidence to press charges. They interviewed group members this week but were no closer to taking the case to court.

Rape Prevention Education executive director Kim McGregor said she found it hard to believe the women and girls involved truly consented to what occurred.

"I cannot believe that any young women would step into a gang-rape situation where they would be humiliated afterwards. I doubt any would have consented to that if it was outlined at the first step."

She said consent was not a one-off incident, but a step-by-step process. Consenting to the first part of an engagement did not grant consent for everything that followed.

Quite often people were lured into situations where behaviour escalated beyond their control, especially if they had been stupefied by alcohol, she said.

McGregor said survivors of sexual assault can experience lifelong symptoms of post-traumatic stress disorder, depression, anxiety, and self-harming.