The Bugbear e-mail virus is continuing to cause havoc across the globe.

According to anti-virus firms, it could be the biggest bug of the year so far and will provide a timely warning to those who thought the threat from malicious programs had receded.

The virus can compromise secure transactions and passwords, make computers vulnerable to hackers, disable anti-virus software and distribute confidential e-mails.

"It feels like it is going to be one of the biggest things all year," said Graham Cluley, senior technology consultant at anti-virus firm, Sophos.

Where did it come from?

Experts at virus filtering firm MessageLabs said the virus appeared to be spreading more quickly.

"Today it has started to go a bit mad. Yesterday we had 35,000 reports all day and today we have already had 37,000," said Alex Shipp, senior anti-virus technologist at MessageLabs.

Bugbear facts

Hundreds of thousands of computers infected Mainly hitting home Windows PCs with no updated anti-virus protection Can replicate without user clicking on attachment Compromises secure transactions and passwords

The search for the origin of the virus is now on and there are suggestions that it could have come from Korea or Singapore.

Most of the addresses it uses are generic web ones, but there were a couple which point to Korea and Singapore, say experts.

The majority of infected computers are those of home users who have not updated their virus protection software.

Earlier e-mail viruses such as the ILOVEYOU bug and the Kournikova virus always carried the same subject line and relied on people's curiosity to open the infected attachment.

But Bugbear, and its predecessor Klez.H, can disguise themselves as a random e-mail from a friend.

Clever tricks

It can even choose an e-mail in a different language to confuse users.

How to protect yourself

Contact anti-virus firm Disinfector available from anti-virus websites Patch for Outlook available from Microsoft At work, contact computer support immediately

"Most e-mail viruses are written in English and foreign language viruses don't tend to spread," said Mr Shipp.

Bugbear however can choose a German language e-mail to send itself on in if it is on a German computer, he said.

In the first few days of the virus, users could identify Bugbear by the size of the file which was always 50,688 bytes.

Now it is picking up other viruses along the way, increasing the file size and meaning there is no good way of detecting it.

For some users the virus can spread even if they do not click on the attachment, taking an advantage of a known vulnerability in Microsoft Outlook.

Those who have been infected with the Bugbear virus are advised to contact anti-virus firms for instructions on removing files and for security updates.