Parents were warned today of the dangers of explicit emails and texts being sent to their children.
More than a third of secondary schoolchildren have been sent messages containing sexual content, a survey showed.
Researchers found youngsters are being sent sex texts or “Sexts” — often by their school friends.
The messages contain images of sex acts involving young people and of youngsters — both boys and girls — exposing themselves.
Material is sent to mobile phones via texts, transferred using Bluetooth or uploaded to social networking groups.
The research, carried out by children’s charity Beatbullying, found it was most often not strangers sending the images.
Seven out of 10 of the 11 to 18-year-olds surveyed said they knew the sender personally. A quarter of the messages were sent by the youngster’s current boyfriend or girlfriend, the study showed.
Girls are bullied into taking, and sharing, explicit pictures of themselves, the charity has warned.
Chief executive Emma-Jane Cross said: “We don’t want to stifle young people’s sexual development but it is important that parents and schools understand the rise of sexting so together we can act to stop sexual bullying.
“Politicians must pool together organisations like Beatbullying to create an intervention and prevention task force in schools and the local community.
“This needs to be part of the solution if we are to educate our young people about the consequences of their actions and how to keep safe online as well as offline.”
Beatbullying questioned 2,094 youngsters in England.