Updated

New Zealand police are facing mounting criticism for the way they've handled an investigation into a group of teenage boys who bragged on Facebook about having sex with girls who were drunk and underage.

Calling themselves the Roast Busters, the Auckland teens publicly named some of the girls and continued operating for two years before their Facebook page was taken down last week following a story on local television station TV3.

The case has angered many in the South Pacific nation and raised questions about how rape allegations are handled not only by the police but also by other authority figures including school officials and radio hosts. Two teenage girls have organized marches in New Zealand's three largest cities next Saturday in a protest against what some describe as the country's "rape culture."

In one disturbing video posted online, two Roast Busters teens brag that they take what they do seriously.

"How about you try to go with the amount of girls we do ... it's a job," says one the teens, adding "they know what we're like, they know what they're in for."

Police at first said they'd not been able to prosecute the teens because none of the girls involved had made formal complaints. But they later backtracked, saying a 13-year-old had given evidence in a 2011 video interview, and that they'd spoken to three other girls over the past two years. Police said the involvement of an officer's son with the Roast Busters group had no bearing on how they handled the case.

The country's Police Minister Anne Tolley has ordered an independent investigation into the police handling of the case, while others are calling for the head of the police force, Commissioner Peter Marshall, to resign.

"Parents of young girls need to have confidence that complaints to police about sexual assault are investigated thoroughly and appropriately," Tolley said in a statement.

Marshall has taken the unusual step of posting a video "message of reassurance" on the police website in which he says attitudes toward sexual assault have evolved.

"In the 1970s, for instance, it was no offense for a man to rape his wife," he says in the video. "Can you imagine that being tolerated in today's world? Certainly not. We have come ahead in leaps and bounds, and I can tell you that the New Zealand police are absolutely committed to doing the right thing by complainants who wish to tell us about sexual offending."

Meanwhile, some companies have pulled their advertising from RadioLive after hosts Willie Jackson and John Tamihere interviewed an alleged victim of the Roast Busters, questioning her about her drinking habits and sexual history. Jackson later offered an apology.

And former students of Avondale College in Auckland, where some of the Roast Busters went to school, have started a Facebook page criticizing the high school as fostering "a regressive environment that does not challenge rape culture." The school has rejected those allegations.