Businesses are being warned to prioritise IT security after figures revealed workers spend an average of 30 minutes a day visiting social networking sites whilst at work.

The figures are likely to cause concern among small firms as many of the sites which are browse by employees are not secure.

Data from the poll, conducted by Global Secure Systems and Infosecurity Europe, showed that workers are costing their corporations nearly £6.5 billion annually in lost productivity through looking at these sites.

But although most IT departments are against allowing workers to peruse sites such as MySpace and Facebook, those in HR often encourage their use among employees.

Claire Sellick Infosecurity Europe event director said: "It would appear that most CISO (Chief Information Security Officers) and IT directors loathe social networking sites and if they had their way would ban them completely.

"But what is also coming across loud and clear is that the HR departments actually welcome the use of these sites - so there is a lot of internal pushing and shoving going on between HR and IT over how best to manage these sites."

According to a recent survey by Connect, the two biggest IT headaches for businesses were 'everyday hassles with IT' (37 per cent) and 'security concerns' (32 per cent).