Channel 4 News reveals the extent to which girls are being sexually exploited or gang raped in street gangs across the UK. Paraic O'Brien reports.

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Sue Berelowitz, deputy children's commissioner, is leading a two year inquiry into the problem, which is trying to establish the number of girls being exploited by key gang members - or gang nominals as they are known.

"Of all of the gang nominals our expectation from the evidence we’ve received to date, is that the girls associated with them would all either be at extremely high risk or actually be being sexually exploited in some shape or form," she told Channel 4 News.

"From the conversations we’ve had with individual girls, some of the stories we get are quite heart-rending really in terms of girls being kidnapped, held at gun point, threatened with being, what the public would understand as gang raped."

There is at least one girl being sexually exploited by each gang nomina or key gang member, and an estimated 6000 gang nominals, at least, in the UK, she told Channel 4 News.

Former gang member Isha Nembhard now works with girls in gangs. She has come across some of the most harrowing examples of sexual exploitation of girls by gangs and says it is commonplace. One of the worst cases she worked on involved a group of gang members sexually abusing a young disabled girl.

Read more on girl gangs: Children's commissioner condemns daggering

'They treat you like a sister'

The government is currently trying to assess the scale of the problem. But according to Ms Nembhard, this will be difficult because many girls don't even recognise it as abuse.

"They'd rather be called a slag than say that somebody's assaulting them or sexually abusing them in that sort of way", she told Channel 4 News.

'Rachel' used to be a member of an infamous south London street gang. She explained why girls become involved in gangs in the first place.

So even though you can go through the hells of it, there are pros to it as well. You ain't got a family at home so you make one. They are substitute families because they’re there for you no matter what. 'Rachel'

"Even though there’s the girls that get used and exploited and whatever, there’s also people that actually want to be there for you; actually want to be your friend and things like that," she told Channel 4 News.

"They treat you like a sister, a brother, all these things. So even though you can go through the hells of it, there are pros to it as well. You ain't got a family at home so you make one. They are substitute families because they’re there for you no matter what."

Sexually explicit 'adverts' posted on Youtube

Young girls are also advertising themselves to gang members on social networking sites, Channel 4 News can reveal.

In fact in one case, the Metropolitan Police told YouTube to remove a sexually explicit video clip. The footage showed an under-18 club night in east London, where the majority of children at the event were between 11 and 16, with some looking much younger.

The style of dancing is 'daggering', a sexually explicit style based on Caribbean dancehall moves. The club promoter filmed the event and posted it on his website via YouTube. In one section a young vulnerable girl started dancing with a boy in a way that the police considered so sexually exploitative they asked YouTube to remove it.

DCI Petrina Cribb is the detective who made the intervention. She helps prevent girls from becoming in with gangs and runs a programme for the Metropolitan Police educating girls about healthy relationships.

"Some of the young people were very, very young and dressed in what I would consider to be an inappropriate way, very scantily clad and also dancing in a very, very sexually provocative manner, which is age inappropriate for them," she told Channel 4 News.

She would not be drawn on the details of the particular girl she was worried about. According to her this is about much more than just virtual flirting.

"We’re talking about sexual exploitation, manipulation, coercion into sexual acts, which they may feel they’ve got no option but to go along with."

'When I stabbed him I just felt powerful'

Channel 4 News also spoke to young women who used to hold powerful position within gangs including Tracey. She was at the other end of the hierarchy: a senior gang member. Among her crimes - the random stabbing of a total stranger.

"When I stabbed him I just felt powerful," she said. "Physically I could feel myself breaking his skin. You can feel it. I had this power of this person. I potentially could have taken his life if id stabbed him in the wrong place or the right place if you know what I mean."

The government has asked the children’s commissioner to investigate the scale of the problem of girls being exploited within street gangs across the UK. The Home Office recently made £1.3m available to fund 13 advocates to help girls who want to leave gangs. According to one study girls in gangs are 10 times more likely to be a victim of crime than they are to be a perpetrator of it.