AGE limits must be imposed on social networking sites in order to protect young and vulnerable users, an internet safety watchdog has warned.
The EU Kids Online network said that while age limits do exist on many sites, there still needs to be an effective method of age verification.
Its research found that a quarter of 9 to 10-year-olds and more than half of 11 to 12-year-olds use social networking sites. Four in 10 give a false age.
Facebook and Twitter this week admitted they cannot prevent young children from setting up secret accounts that can be used for cyberbullying.
Simon Milner, a senior executive with Facebook, said that it was almost impossible to police illegal use of such sites, which generally have a minimum age of 13, by minors.
Patricia Cartes, head of Global Safety Outreach Public Policy at Twitter, also said: "We haven't found a silver bullet in the online industry to meaningfully verify age."
EU Kids Online, a network of researchers in over 30 countries in Europe, has now issued a policy report outlining recommendations for a safer and better internet for children.
Its new report says Government, the EU Commission, the industry, parents, teachers and children themselves all have a role to play in tackling online risks and abuses.
The industry can play a major role by developing new products and services dedicated to the needs of children.
Report author Brian O'Neill, of Dublin Institute of Technology, said: "Young people need support from their parents, teachers as well as from industry.
"However, they also have to take responsibility for their own actions and behaviour online."