Fans playing web-based games and keeping up to date with scores and results online will make the four weeks of the Fifa World Cup tournament the least productive time during 2006 for businesses. 

The time wasted will cost the average UK business £8,400 in lost productivity for every 100 people it employs, according to web content filtering vendor Marshal. 

"Every major sporting event sees the same pattern and, because of the popularity of football, the four weeks of the World Cup are certain to be the least productive of the year," said Marshal chief executive Ed Macnair.

The majority of the UK's estimated 17 million football fans work in desk-based jobs, and internet access during working hours will be their prime source for the latest on the tournament.

Marshal said that the World Cup could also affect companies' IT services, as fans eat up valuable bandwidth by downloading videos and interactive scoreboards.

Macnair urged employers to set policies for acceptable internet use. "By implementing policies to limit internet access to certain sites to lunch time, and before and after working hours, companies are able to control productivity and corporate bandwidth issues," he said.