According to a report, only one in eight children in Britain will report seeing upsetting sexual content on the Internet.
The study conducted by the London School of Economics revealed that just 12 per cent of children use the reporting tools on websites.
The report found that almost a fifth of children reported upsetting sexual messages they had encountered online, while just 15 per cent reported upsetting sexual images.
Fourteen percent of children aged 9-16 said they had seen sexual images online.
Two percent said they had seen violent sexual images, the Telegraph reports.
According to the survey, one third of children who had reported upsetting material online said they did not find the response to be helpful.
EU Kids Online project has pointed out that children need simpler and more accessible tools so that they can raise concerns.
"Given the relatively low take-up of online reporting mechanisms, there is considerable scope for further promoting their availability, age-appropriateness and use," the paper quoted Professor Sonia Livingstone, the director of the EU Kids Online project, as saying.