A quarter of children have sent or received an email containing inappropriate content, says TalkTalk.
According to research by the ISP, as part of its Brighter Sparks campaign aimed at making parents aware of how to look after kids online, 11 percent admitted they had bullied or been bullied online, while 5 percent have engaged in communication with a stranger via a webcam.
Furthermore, two percent admitted to meeting a stranger in real life they had first contacted online.
TalkTalk said a quarter of kids think their parents are completely oblivious when it comes to what they get-up to online, while 62 percent claimed they lie to their parents about what they look at on the web and 53 percent delete their browsing history to parents can't discover what they've been up to.
More than half (55 percent) believe they know more about the web than their parents and 47 percent reckoned they had at least two hours unsurpervised browsing time every day.
Tristia Clarke from TalkTalk, said: "Our research underlines the need for greater communication between parents and children - it's the best way for parents to get a sense of the likely risks to their children and therefore manage and minimise them where possible."
The reseach was conducted via the eParent test on TalkTalk's site, which was designed by Professor Tanya Byron, author of the Byron Review.
"The internet doesn't have to be a dangerous place for children and in fact can be hugely beneficial to their development and education," Byron said.
"As long as parents are armed with effective tools they can ensure their children are spending time online safely and responsibly. But it's crucial that parents educate themselves about what's going on online and what their kids are doing there."
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