The average British employee spends around 90 minutes per week surfing the web for personal use, a new study by the Confederation of British Industry (CBI) has revealed.A survey of 503 organisations found that around ten days are lost annually as a result of employee internet use, costing the economy over £10 billion per year.Commenting on the results, CBI deputy director John Crindland said: "Nobody wants to behave like Big Brother and there is no epidemic of misuse, but there needs to be a bit of give-and-take from all parties. Employers need to decide for themselves what level of non-work surfing is acceptable and then set out clear boundaries."Mr Crindland added that internet use could also help to improve productivity and boost morale and said that employers should not necessarily view the time as "wasted".A number of companies have already banned employees from accessing social networking sites, including British Gas and Credit Suisse.