A group of young Auckland men are recruiting other boys through Facebook to join them in group sex sessions mostly with drunk teenage girls. The problem starts when the males publicly name their female partners through the popular social networking site, reports 3 News.

The male group, made up of 17- and 18-year-olds, is known as the Roast Busters and was formed in 2011. The police said they have been investigating the group since then.

The naming of the underage girls, often drunk, they have sex with is done in videos that the Roast Busters started to post in Facebook five months ago.

Explaining their group name, one young man in the video said, "A true roast is where you know you are going there intentionally to roast this female ... We don't choose a roast, the roast chooses us. We have girls hitting us up to 'hang out with us.' They know what we're like, they know what they're in for."

Another young man said they take what they do seriously. "This is hard, it's a job, we don't do this shit for pleasure," he insisted.

One of the female victims told 3 News that she was raped by three guys at one time because she was too much intoxicated. Police said they had interviewed a couple of the female victims over the past two and a half years they had been tracking Roast Buster's Facebook page, which they pointed out is morally wrong but not a crime.

Although the Facebook group had been shutdown since Thursday, detective inspector Bruce Scott said that none of the victims were brave enough to make a formal statement which is needed to prosecute the Roast Busters, probably due to trauma.

Until the girls make a statement, all the police could do is warn the Roast Busters members.

"We've told them their behaviour is verging on criminal if not criminal, and suggested it cease ... Some of the boys and their families were compliant and we believe they have stopped associating with the group," Mr Scott said.