"The high rates of sexual coercion discovered need to be addressed through education and awareness raising that challenges attitudes and helps change behaviour"
Most were pressured to have sex or other sexual activity, but some cases included rape. And many of the 13-17-year-olds had also suffered physical attacks, intimidation or emotional abuse from their boyfriends.
The research also found that a high proportion of teenage boys regularly viewed pornography and one in five harboured extremely negative attitudes towards women.
The research in England was undertaken between 2013-2015 by a team of researchers from the Universities of Bristol and Central Lancashire. The study, was also carried out in Norway, Italy, Bulgaria and Cyprus as well as England. It is one of the biggest of its kind ever undertaken in Europe, involving a school-based survey of 4,500 children and 100 interviews with young people
Lead author Dr Christine Barter, NSPCC Senior Research Fellow who is based at Bristol's School for Policy Studies, said:
"Our research findings show that across Europe violence and abuse, both offline and online, in young people's relationships constitutes a major problem, yet in most countries it remains unrecognised leaving young people with little support or appropriate services."
Nicky Stanley, Professor of Social Work at the University of Central Lancashire and co-author, commented:
"Teenage girls reported serious distress and harm following abusive behaviour from boyfriends. Education and campaigns need to challenge stereotypical behaviour and attitudes in boys and the law in this area should be clearly communicated to young people, their parents and teachers."
The NSPCC is now calling on the government to take action to ensure teenagers get a clearer message about healthy relationships.
Claire Lilley, head of child safety online at the charity, said:
"The levels of victimisation revealed by this research shows action is urgently needed by the government to make updated sex and relationship education a statutory right for every child and young person. There needs to be a greater focus in schools on topics such as sexual exploitation and violence against girls and young women, as part of a balanced curriculum.
"The high rates of sexual coercion discovered need to be addressed through education and awareness raising that challenges attitudes and helps change behaviour. We need to nurture children to have positive relationships based on mutual respect."
The highest rates of sexual coercion were reported by teenage girls in England.
Around one in five (22 per cent) also said they had suffered physical violence or intimidation from boyfriends, including, slapping, punching, strangling and being beaten with an object. In interviews with 100 of the children, many said the pressure to have sex was so great it almost became 'normal' and in some cases rape was not recognised.
Katie, a 15-year-old who took part in the survey in England, said:
"I've had relationships where I wouldn't be able to go out with my friends because they'd get angry with me. I have been raped and other things like that". Amy, also 15, said of one boyfriend: "He breathed down my neck 24/7, it was horrible."
Almost four in ten (39 per cent) boys in England aged 14-17 admitted they regularly watched pornography and around one-fifth (18 per cent) strongly agreed with statements such as: "It is sometimes acceptable for a man to hit a woman if she has been unfaithful." And: "Women lead men on sexually and then complain about the attention they get."
Controlling online behaviour by partners, through constant checking of their social network activity, sending threatening messages or telling them who they could be 'friends' with was closely associated with young people experiencing violence or abuse from their partner offline.
Young people who reported violence and abuse in their relationships were at least twice as likely to have sent a sexual image or text compared to those who had not.
England had the highest rate for children exchanging sexual images and messages with a partner among the countries surveyed. More than four-in-ten (44 per cent) girls and just under a third (32 per cent) of boys in England had sent them to their boyfriend or girlfriend. Just over 40 per cent of girls who sent them said they had been shared by a partner with others.
Just under half of girls and boys in England had received them. Around a quarter (27 per cent) of girls sent messages and images because they felt pressurised by a partner to do so.
The research, available to view here http://www.stiritup.eu, was funded by the Daphne III European Commission.
The original rainbow flag, called the Freedom Flag, was devised by Gilbert Baker in 1978. The design has undergone several revisions since its debut with 8 colored stripes, and today the most common variant consists of 6 stripes: red, orange, yellow, green, blue, and violet.
Picture of Gilbert Baker's original Freedom Flag showing the meaning of the 8 colors.