A 15-year-old girl who says she was a victim of the Roast Busters group made a complaint to police two years ago, contradicting the official line that they could not prosecute members of the gang because no one had complained.
The girl, who was 13 at the time, told 3 News this evening she was sexually assaulted two years ago by members of the gang, who have bragged on Facebook of getting underage girls drunk and having sex with them.
She was left traumatised and after plucking up the courage to tell her family two weeks later, her parents took her to police to lay a complaint.
Her brother also gave police the names and addresses of her attackers.
"I had a video interview where I had to act out what had happened with dolls ... it was traumatising," she said.
The girl, who cannot be identified for legal reasons, told 3 News she felt it was her word against the Roast Busters and no charges were laid.
"This is my chance to say something. I couldn't do anything two years ago. I want to do something now," she said tonight.
She believed she was one of the gang's first victims and said if action had been taken, she could have prevented it happening to other girls.
Until this evening, police have maintained that they have been unable to prosecute any of the Roast Busters gang because no victims had laid a complaint.
Police confirmed to 3 News a complaint involving the Roast Busters was received in December 2011.
"An investigation was launched and the complaint was thoroughly investigated," police said in a statement to the broadcaster.
"Whilst this was a distressing situation for the girl and her family, police determined that there was not sufficient evidence to bring a prosecution.
"Police discussed this matter again with the victim's family this morning and restated their absolute commitment to doing their best by their daughter."
The girl intended making another complaint tomorrow, according to 3 News.
Labour's police spokeswoman Jacinda Ardern said the party would tomorrow lay a complaint with the Independent Police Conduct Authority over the alleged handling of the girl's complaint.
"The revelations tonight by one of the victims that she made a complaint to the police at the age of 13 and the nature of the interview that she had has led us to believe that this absolutely needs to be reviewed independently to ensure that ... the police acted appropriately in the way they handled that 13-year old child," Ms Ardern said.
Any review should also ensure that police took the investigation as far as it could have gone "because certainly the public's expectation from the information available is that actually, charges would have been able to be laid because this is a case that ultimately has involved a child," she said.
Labour was stepping in to make the complaint because such victims should not have to approach the IPCA as well as deal with their experience with police, Ms Ardern said.