The ever-increasing deluge of junk email and viruses means that PCs are taking more 'sick days' than their owners.

Research by Yahoo Mail among 2,500 UK email users found that the average PC is out of action for nine days a year.

The study found that PCs are out of use for a total of 49 hours, more than six 'working days', while their owners battle spam. Another three days are lost due to viruses.

Figures from the Confederation of British Industry indicate that UK workers take on average seven sick days a year.

The study claimed that the equivalent to two per cent of the average worker's salary (£463 out of £20,000) is wasted on spam-fighting chores.

Yahoo! Mail found that 70 per cent of UK PC users have fallen victim to a computer virus over the past year.

Less than 50 per cent of users are aware that computers get viruses by opening attachments, while only 17 per cent know that you can get a virus by downloading a file.

Over three quarters of UK surfers claim to delete any spam they receive, while just over half have notified their ISPs and expect them to take action. Some 16 per cent admitted that they reply to junk emails.

E-commerce minister Stephen Timms said in a statement: "Nobody - be it government, industry or otherwise - can work alone to eliminate the problem overnight.

"If we are to have an impact on reducing spam, the fight demands international co-operation and collaborative campaigns."

James Bilefield, European head of Yahoo Mail, added in a statement: "We work very closely with industry bodies to hit spammers hard at the source through legal initiatives.

"But the key for users is finding a balance between having the very best technology tools coupled with a basic understanding of how they can personally stop the perpetuation of spam."