Unwanted emails and computer viruses are costing UK businesses a massive £10 billion a year to deal with, new research has revealed.

A study by Yahoo! Mail found that firms spend £6.7 billion dealing with spam and £3.3 billion protecting PCs from viruses every 12 months.

Yahoo! Said that spam and viruses cause UK businesses’ computers to have an average of nine ‘sick days’ a year while they are out of use or being repaired.

This is costing small firms millions of pounds in the resulting drop in productivity and lost business. By comparison, the average employee takes just seven days off sick a year.

The problem of spam and large computer viruses, such as the SoBig virus launched earlier this year, has become a major headache for small businesses, who often do not have adequate protection for their computers.

Although new anti-spam laws in the UK have cut the number of unwanted emails originating in Britain, small firms’ inboxes continue to be clogged up by junk mail from the USA.

Providers AOL, Microsoft and Yahoo! have teamed up to try to solve the problem of spam, but many entrepreneurs are failing to see any real benefits so far.

James Bilefield, of Yahoo! Mail, said that it was unrealistic to expect that all spam could be eradicated.

“However, our battle plan has a sound three pronged attack – technology, education and legislation.

“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,” he said.