Computer security experts are divided on the seriousness of a new computer virus spreading through office networks in Asia, Australia and Europe.

Called "beagle" or "bagle" it comes from a familiar email address with the subject field "Hi". If the recipient clicks on an attachment a worm is then dispatched to his or her address book in search of more people to send itself to.

It started spreading yesterday through an attachment appearing to be a calculator but virus experts were sceptical that it could become a big problem.

David Perry, spokesman for anti-virus firm Trend Micro, said most people knew better than to click on attached calculators.

"It's clumsy," he said. "I don't get e-mails with calculators in it, do you?"

The virus only affects machines running Microsoft Windows operating systems.

Carey Nachenberg, chief architect of Symantec Research in California, said home users were most at risk because companies had protected themselves quickly.

"We could see this fizzle out in several days. Or we could also see a lot of people infected if they don't update their anti-virus software."

The virus has had little impact in North America, where many office workers were on holiday as the virus yesterday spread in other parts of the world.