The level of sexual violence in gang-afflicted neighbourhoods is comparable to that seen in war zones, according to the author of a new report.

"In some areas the level of sexual violence and the types of violence inflicted are comparable to how sexual violence is used in war-torn territories," said Professor Jenny Pearce of the University of Bedforshire, lead researcher on the sexual violence report for the Office of the Children's Commissioner.

The report – entitled It's Wrong But You Get Used To It – found that girls as young as 11 are being systematically groomed, exploited and raped in the worst gang-affected areas of the UK, with the peer-on-peer violence going undetected, unreported and ignored.

Sue Berelowitz, the deputy children's commissioner, said rape was widespread and happened "on a daily basis" in the worst-hit areas.

"As soon as a girl has had sex, coerced or otherwise, it is completely open season on her. She has abrogated all right to refuse to have sex with someone for all time. They will and do have sex with her any time, any place and anywhere," she said.

She added that the "sheer levels of sadism" uncovered by the inquiry had been shocking.

Of the 188 young people and 76 professionals questioned, 65% shared examples of young women being coerced into sexual activity; as one 18-year-old put it: "Once they've implemented that fear into them it's easy to get what you want."

Half of respondents shared examples of girls having sex in return for status or protection, while 41% identified examples of rape and 34% of gang rape.

The report also gives an insight into the hierarchy of gangs and the place of girls within them.

Girls identified as "wifeys", or girlfriends, of a high-status gang member, were often called upon to hold drugs, weapons and money while also being at risk of rape or physical violence from opposing gangs. One 21-year-old man said his girlfriend was at risk of being beaten up, or stripped and forced to walk home naked. "That's why mine is always close to me [...] I don't let her go far," he said.

But other girls, identified as "links" – girls in casual sexual relationships with gang members – were in an even more precarious situation, also under pressure to hold illegal goods but also at risk of multiple rape.

"[She thinks] these people are going to look after me and they care about me […] that female usually ends up getting a name … whore, sket, dirty girl, smig," said one 27-year-old male. Other girls were identified as "gangster girls" who "goes and dresses like a man, the gold and the tattoos […] a tomboyish girl who's willing to hold a gun when needed. One of those brave ones."

They were spoken of with admiration by other girls, noted the report, because they were seen "as largely protected from vulnerability to sexual exploitation and sexual violence".

Only one in 12 interviewees – 32% of whom said they were black British, while 28% were white and 21% dual heritage – felt that young people would be likely to speak out about or report sexual violence or exploitation . As one young woman put it: "It's normal … It's wrong, but you get used to it … Welcome to our generation."

Many of those questioned had little concept of ideas of sexual consent, with girls presumed to consent to sex – even with armed multiple perpetrators – unless they "fought off" their attackers.

One 16-year-old youth described an occasion when seven young men had coerced a woman. "Not rape, it's just that that girl had wanted it to happen, or not necessarily wanted it to happen but she basically asked for it." Another a 17 year old man said: "If she looks like a ho then the boys will treat her like a ho... and she has no choice but to accept how they're treating her."

John Pitts, a researcher for the report and an expert on gangs, said he had been shocked by the "normality" of the violence reported. "There was a acceptance or resignation of the brutality of their lives," he said. "These young people are very difficult to get to, but when we did we found sexual violence appeared to be routine and regarded as unexceptional. For many of them this was the wallpaper of their lives." Pitts warned that the cutting of youth services – between 2010 and 2012, cuts averaged 27%, while 19 English councils slashed services by half and a handful withdrew them entirely – exacerbated the problem.

Matthew Reed, chief executive of the Children's Society, said: "Schools, health and youth services must get better at teaching children about healthy relationships. They need to teach both boys and girls about what consent means, so children can protect themselves from becoming involved in exploitation."

Anne Longfield, chief executive of the charity 4children, said the problems which allowed sexual exploitation to happen had to be tackled early, before children were in touch with the criminal justice system. "This is a wake-up call for all those who don't think that closing the doors of places where young people can go does not have consequences," she said.

In January the education secretary, Michael Gove, said youth policy was not a key government concern – an attitude that will leave girls facing routine and brutal abuse, said Pitts.

"There is a complete abrogation of responsiblity by central government," he said. "What we have seen in this report is the consequences of the marginalisation and emisseration of some of our neighbourhoods, and we have a responsibility to bring those drifting areas back into the mainstream."