One in five 11 year olds have been found to be illegally downloading music from the internet, according to a study for Childnet International.

Kids also did not know that their parents could face legal action if the household account is identified as being used for unlicensed file-sharing.

The study of 1,000 11-16 year olds, found that most children, 73%, are introduced to illegal file-sharing websites by their friends.

More than half (53%) of 11-16 year olds now access the internet unsupervised from their bedrooms, or while out an about on smartphones.

Professor Tanya Byron, child psychologist and author of 2008's Safer Children in a Digital World is supporting internet safety charity, Childnet International, to help parents and teachers talk to teens about safe and responsible internet use.

Byron said: "The majority of parents will confidently tell their children that it is wrong to steal or shoplift in the real world, but it's vital that they also help kids understand what is and isn't acceptable behaviour online, and why it's just as harmful.

Lucinda Fell, Director of Policy and Communications at Childnet International, said: "We know that many parents are concerned about keeping up with what their children are doing online. We know from our work in schools that parents often tell us they are confused about what can and can't be done safely and legally online."

Last week, it was found that 50% of children between 7-12 are using Facebook against the site's usage policy. Children in that report said that pester power forced parents to let their under 13s use the site.

Unlike illegal sites, Facebook actively bars under 13s from their site, but provides a legal and safe forum for listening to music for children older than 13.

Spotify and other new 'social apps' on that site are a legal way to listen to and share music online. Spotify users have increased by 4 million new users since the Facebook integration was announced at F8 on 22nd September.

Parenting blogger Janis Curry from ReallyKidFriendly.com said: "The use of illegal file sharing websites like Pirate Bay is unsuprising - kids have a voracious appetite for new music, and 79p is quite steep when they know the free version is out there somewhere,

"Our generation walked to the local record shop and bought singles and LPs - although some people may have sneaked out with a record under their shirt, most people expected to pay for music.

The best we can do as parents is to help our kids understand that what they're doing is an online version of shoplifting, and hope that their morals prevail... That, and give them a monthly allowance for buying music online through TuneChecker.com."

Research from Ofcom in 2009 found that children as young as five were using the internet without supervision.

The Childnet Music, Film, TV and Internet guide is available at Childnet.com.