If the internet at its worst is a lair for child predators, child safety folks have the best of reasons to worry about social networking sites, where members are invited to post all sorts of revealing information about themselves.

Now they have even more reason to worry.

A just-released study reveals that a large numbers of 8- to 11-year-olds are flouting age restrictions and creating profile pages on sites meant for teenagers and young adults.

More than a quarter of kids 8-11 who know about social networking sites have put up profiles, according to the study by Ofcom, Britain’s communications watchdog.

And if it's the case in the UK, it's probably so in the U.S. as well, warns Will Gardner, deputy CEO of Childnet, an international children’s charity that campaigns on internet safety issues. “I wouldn’t think it would be that different.”

The Ofcom research, based on interviews with 7,000 Brits, shows just how popular social networks have become in their short history.

Among internet users, 22 percent of people over age 16 have profiles, and among users 8-17 that figure shoots up to 49 percent.

Among 8- to 11-year-olds who know about social networks, 27 percent told researchers they had profiles. While some were on age-appropriate sites like Club Penguin, Ofcom found that large numbers were on sites like Facebook and MySpace, which typically require members to be at least 13 or 14. Ofcom cites Nielsen data showing that 15 percent of 6- to 11-year-old surfers have used Bebo, 4 percent have used Facebook and 8 percent MySpace.

Of course, what worries child safety groups is the lack of savvy among children about the nasty people lurking about online and how to protect themselves, and the Ofcom study confirms those concerns are well founded.

It found that 41 percent of kids 8-17 leave their privacy settings on open, meaning anyone can view their page, and 34 percent of 16- to 24-year-olds post sensitive information like addresses and phone numbers.

“Very few kids would write their name, address and phone number down and hand it out in Victoria station. But online they put all the information up there,” notes a spokesperson for Britain’s Child Exploitation and Online Protection Centre, an organization that works to eradicate sexual abuse. “We would say, think carefully because these two worlds are one and the same.”