The TUC has warned businesses against checking up on potential recruits using MySpace and Facebook, but says staff should be allowed to use social-networking sites during work hours.

Britain's trade union umbrella group has emphasised the need for workplace policies covering the use of email and the web, including social-networking sites, warning that employers who "take equal opportunities in recruitment seriously should not be tempted to check out the profiles of job applicants on Facebook."

Only a minority of potential recruits will have public profiles on Facebook and MySpace, so using information from this source can give an unfair advantage or disadvantage to certain candidates, the TUC said.

Without proper workplace policies, "the UK's Facebook users are 3.5 million accidents waiting to happen," the TUC said.

The TUC advice suggests that whilst employers are completely within their rights to forbid staff from using sites such as Facebook, MySpace or Bebo in work time, a total ban may be something of an over-reaction.

"Simply cracking down on use of new web tools like Facebook is not a sensible solution to a problem, which is only going to get bigger, " said TUC General Secretary Brendan Barber.

"It's unreasonable for employers to try to stop their staff from having a life outside work, just because they can't get their heads around the technology. Better to invest a little time in working out sensible conduct guidelines."

The guidance states that it not acceptable for staff to spend hours a day on social-networking sites when they should be working, but calls for policies drawn up with the involvement of staff.

The union body also recognises employers' concern about the dissemination of businesses information on social-networking sites.

"Employers may have valid concerns about commercial confidentiality or reputation damage, but in most cases they should not over-react by attempting to stop staff from using such tools to help organise their personal lives."

Andrew Brown, Technical Manger at web security company SonicWall said, "Controlling access to online content is not the problem that some managers seem to think it is."

Content management products can not only filter downloads they can, for example, block access to social-networking sites except for lunch breaks.