TUC spokesman John Wood said the organization decided to issue its guidance -- which is directed both at employers and employees -- because of the growing hype surrounding the use of Facebook in the workplace. "There's a bit of a panic here in the U.K. about Facebook," Wood said. With about 3.5 million registered users in the U.K., Facebook is becoming an increasingly popular social networking tool in Britain even as it is being banned in a growing number of workplaces, he said.

Much of the "hysteria" is the result of misplaced or uninformed concerns about the negative consequences of social networking sites at work, he said. "The issue that seems to be worrying employees is cyberslacking. But we don't see this as a particularly new phenomenon."

Employers in the past have shown a certain willingness to allow their employees to use the Web in their downtime, and there is no reason to change that attitude, he said. "They seem to be overreacting to this Facebook issue just because it's such a hyped story."

According to the TUC's guidance for employers, companies should recognize that the issue won't go away simply by banning Facebook from the workplace. The goal, instead, should be to have a clearly articulated and open "conduct policy" regarding the use of such sites, coupled with a hands-off approach to an employee's personal life. This is especially important given that the use of social networking sites is likely to become the norm -- especially among younger workers going forward, the TUC said.

"Actively engaging with an issue that is not going to go away is the best way to ensure that there are no unpleasant surprises for both employers and employees," it noted.