According to a DataMonitor survey of European firms, the net is fast becoming a major source of distraction at work with employees looking at non-work related and offensive content, particularly pornography.
With employers worried that surfing at work can lead to reduced productivity and possible litigation, they are increasingly looking for effective ways of controlling the net content their employees have access to.
Of the two-thirds of firms which monitor content, 40% say they do so on a regular basis.
Too distracting
The net at work
Two thirds of firms have written policies on use of net
59% place restrictions on net use
Over half of these use a software solution
One fifth manually check internet history files
Over half of the firms interviewed claimed to restrict access to some sites, with pornography unsurprisingly high on the list of banned urls.
Companies are increasingly worried about the threat of litigation from sensitive employees offended by the presence of salacious content.
They are also worried about the amount of time employees are devoting to personal surfing.
"Companies have realised that the internet can prove to be as much as a distraction as a means by which to improve efficiency in the workplace," said DataMonitor analyst Adrian Drozd.
"Indeed, non-related web usage can have a considerable impact on employee productivity," he said.
The survey of 200 European companies appears to contradict a survey into UK bosses attitudes from Star Internet.
That study found that half of UK businesses had no idea what their employees were doing online with one in three bosses actively encouraging use of the net for non-work reasons in order to promote a positive working environment.