Social networking costs UK plc £6.5bn a year

The average worker spends three weeks a year on sites like Facebook, Bebo and Myspace

Facebook is costing business billions

The use of social networking sites by employees is costing UK corporations almost £6.5bn a year, according to a poll.

Staff are spending an average of three working weeks per year on such sites, says the poll of 776 office workers by Global Secure Systems (GSS). And some of the companies surveyed said that Facebook consumed as much as 30 per cent of their bandwidth.

But banning them can also cause problems, said GSS managing director David Hobson.

"Social networking sites are now integral to the way that many of the latest and youngest recruits into the workforce communicate and work," he said.

Lost working time is not the most serious worry, according to David Lacey, a member of the British Computer Society (BCS) Security Forum.

"Organisations have a very long way to go in getting to grips with the risks, " he said. "Lost productivity is the tip of the iceberg - the threat to sensitive information is real and growing."