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 have not said whether anyone was in the house at the time, or who the suspect is, though news reports have said he - or she - is 23 years old.

Police originally thought the main suspect was male but now say they are looking for a female computer school student from a middle-class family.

The FBI and Interpol helped track the virus to the Philippines through an electronic trail left by the rogue e-mails.

US security experts said clues in the virus code pointed to a student at a computer college in the Philippines.

Bjoerck: Programmer is a German

But Swedish researcher Fredrik Bjoerck said traces on the internet pointed to a German exchange student living in Australia.

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.

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

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.

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

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

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

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

"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."

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

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

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.