The Information Commissioner's Office (ICO) has warned UK teenagers that they may regret posting personal details on social networking sites.

A survey of over 2,000 teenagers found that 71 per cent would not want a college, university or potential employer to see information posted on a social networking site such as MySpace or Facebook.

David Smith, deputy commissioner for the ICO, said: "Many young people are posting content online without thinking about the electronic footprint they leave behind.

"The cost to a person's future can be very high if something undesirable is found by the increasing number of education institutions and employers using the internet as a tool to vet potential students or employees."

The survey found that 95 per cent of teens are concerned about how the information they post is used, but barely a third read the privacy policies of sites they sign up to.

One in six people have posted their date of birth online, a quarter have posted their job title and nearly 10 per cent have posted their home address.

Names of siblings and parents are also routinely put online, generally acting as passwords.

The ICO warned that many social networking pages are not deleted even if they are deactivated, and that many blogging sites can be recovered after being shut down.

The ICO has set up a website for young people aimed at helping them to protect personal information online.

"We have to help teenagers wise up to every aspect of the internet age in which they live. It may be fun but unfortunately it is not the safe space many think it is," Smith concluded.