Some of the worst cases of sexual bullying are inflicted by girls on other girls, with words such as "virgin" used as insults between pupils as young as 13.
Research by Neil Duncan, of Wolverhampton University, reveals that such bullying often becomes so extreme that victims have to move schools mid- year.
Sexual bullying of girls by girls is often overlooked, despite the media attention focused on similar bullying by boys. Earlier this year, a BBC Panorama documentary highlighted the problem of male sexual bullies in schools.
But Dr Duncan, who has spent more than 10 years researching the issue, argues that sexual bullying among girls is a growing problem.
He points out that girls tend to conflate the notion of popularity with the ability to be successful with boys.
"If you ask young people what boys fight about, you will get a variety of answers, such as sporting allegiances, who runs faster and even who is the better fighter," he said. "But ask what girls fight about and the answer is nearly always boys."
He interviewed 15-year-old girls at seven schools throughout the North West and the Midlands. He found that, in any school with female pupils, there was usually a social hierarchy in which popular girls held influence over their peers.
These girls tended to be feared socially, and transgressing their fashion, friendship or dating codes had negative consequences.
Classmates are under pressure to have the ideal physique, to wear the right clothes and to have the correct hairstyle.
Even the slightest deviation from the "perfection" embodied by popular girls can lead to victims being labelled promiscuous or not sexy enough.
The popular girls also have the power to prevent relationships from forming between boys and girls. Fifteen-year-old Claire told Dr Duncan: "If a popular boy likes a girl, the popular girl turns round and says, `You can't go out with her, she's ugly', and the boy will back down. They're scared."
In all cases, victims are ostracised through sexualised name-calling: slag, whore, bitch, lezzie. Unexpectedly, weaker girls were also referred to as poofs.
"I have no need to list the scurrilous names used by bullying girls," said Dr Duncan.
"But they mostly centre on pathological promiscuity, lesbianism, dirtiness, and the incapability of getting, pleasing or keeping a male .
"The word `virgin' was used as a slur against modest girls. When 13-year- old girls are using `virgin' as an insult, it says something very powerful about the peer culture and its values."
Many girls faced with such consistent attacks feel they cannot continue going to school. Far more than bullied boys, girls are likely to feign sickness or play truant to avoid the problem.
In more severe cases, girls try to move schools. Often, as bullying leads to plummeting grades, this is seen as a viable option.
"The student might suggest that a move to a new school would help reduce distractions and lead to better performance," Dr Duncan said.
"Most parents, unaware of the real underlying problems, would see this as a plausible and mature response to falling grades."
He suggested that schools should automatically look for evidence of bullying whenever a pupil requested a move. Such issues should then be tackled by teachers.
"The competition for social esteem is often inflected through gender identity and sexual reputation," said Dr Duncan.
"By reflecting back young people's attitudes, beliefs and behaviours to them, we can often effect . meaningful change."
Girl power's dark side
- Sexual bullying of girls by girls is often overlooked, despite the media attention focused on similar bullying by boys.
- Popular girls will use sexualised insults to ensure that classmates conform. "Virgin", "poof" and "lezzie" are common terms used. Popular girls will also persuade boys not to date their victims.
- Girls are more likely than boys to skip school to avoid being bullied. In the most extreme cases, victims will ask to move schools to escape the problem. But schools might be unaware that this is the reason for the request.