Tackling the virus

Do not open it Delete it using shift del As with all e-mails, if in doubt do not run any attachments you are not expecting If you have run the attachment, isolate your machine from any network and phone your help desk or seek expert advice Remember to keep your anti-virus software up-to-date and be vigilant about attachments

They had previously believed the culprit to be a 23-year-old man. But they now said they were looking for a young female computer school student from a middle-class family.

"With all the publicity in the last three days, we fear that she has destroyed by now all evidence that could link her to the hacking," said an official.

Traced to Philippines

The FBI and Interpol have been helping in the hunt for the lone programmer who invented the virus. They tracked the virus to the Philippines through an electronic trail left by the rogue e-mails.

But officials in Manila have raised the possibility that the suspect might not be responsible for the computer attack.

Bjoerck: Programmer is a German

"It was only the computer used to launch the virus that was traced but anybody could use that computer," said an official.

"The user here is invisible, it could be anybody. The difference is that the person we have identified is the registered owner of that computer."

And Swedish researcher Fredrik Bjoerck, who helped find the creator of the Melissa virus, said traces on the internet pointed to a German exchange student living in Australia.

Copycat alert

The virus caused a flood of e-mails with the alluring subject line ILOVEYOU to course through computer systems in more than 20 countries on Thursday.

Several variations appeared soon after, one masquerading as an e-mail joke, another as a receipt for a Mother's Day gift.

Worldwide infection

3.1 million files worldwide 2.5m in North America 325,000 in Europe 129,000 in Asia 25,500 in Australia and New Zealand Source: Trend Micro Inc

Anti-virus software maker Symantec said the latest variant of the virus poses as a warning message from their technical support team. Infected e-mails have the subject line Virus ALERT! and should be deleted.

Experts say the virus is likely to engender more variants in the coming weeks.

E-mails infected with the Love Bug reached 45 million users, according to one estimate.

It only affects systems running Microsoft Windows with Windows Scripting Host enabled. Computers using Apple's operating system or Linux are not affected.

Estimates of the worldwide damage from the virus range from hundreds of millions of dollars to $10bn, mostly in lost work time.

Although the virus seems to have started in the Philippines, systems there and in much of Asia have escaped largely unscathed as several markets were on holiday last week.

The full extent of the virus will likely become clearer on Monday.