The VirusEye monitoring service run by security firm MessageLabs said the UK has been hit the hardest.
On Monday afternoon (7 October) MessageLabs reported that its virus scanning service had stopped more than 321,00 occurrences of the Bugbear virus worldwide. Some 183,667 of these were in the UK, 20,618 were in Australia and just 20,021 in the USA.
Reacting to the impact of Bugbear, Mark Sunner, chief technology officer at MessageLabs, said: "There have been few new viruses in 2002 although levels of virus activity have never been higher."
Bugbear, which originated in Malaysia, has been disrupting e-mail users since 29 September. The virus replicates by attaching itself to a copy of the body text from legitimate e-mail messages in a user's inbox.