The Government's information commissioner has warned young people to think twice before putting personal details on their profile pages on social networking websites such as Facebook and MySpace.

The watchdog is concerned that young people aged 14-21 are being naïve about the personal details they let others see on social networking websites.

More than half of young adults said they made most of the information posted on Facebook, MySpace or Bebo public for others to see, according to a survey by the Information Commissioner's Office (ICO). Two-thirds admitted to accepting people they didn't know to become friends.

Electronic footprint

60 per cent of the 2,000 respondents did not realise the information they publish on leaves an electronic footprint that can spell trouble in their future careers.

"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," David Smith, ICO deputy commissioner said.

Protect passwords

The information commissioner advised young people to protect their passwords and keep their geographical location secret.

A Facebook spokesman said the firm takes security issues 'very seriously'. "We ... try to make sure users are educated. But we're a technology company, this socialisation of the web is happening at such a rapid pace," Owen Van Natta, an executive at Facebook, told The Guardian newspaper.

The ICO has launched a new website to help young people understand their information rights.