Klez threat upgraded to 'severe'

Antivirus experts have upgraded the Klez virus threat in response to an overwhelming number of submissions of infected material.

Security firm Symantec reported seeing "a few thousand" just yesterday.

Klez retained the number one position of most infectious viruses throughout March, and it looks like April will be no different, according to the statistics.

Symantec has been tracking an average of over 3,000 infections a day in the last few days. By comparison, the SirCam epidemic peaked at only 1,500 infections a day.

As a result, Klez and its variants have been upgraded to a level four threat, which translates as 'severe'. Level five is the most dangerous.

The latest variant spreads as an email attachment via the Windows Address Book, ICQ and local files and shares. Random subject lines and infected files make the worm harder to spot.

Security firms have also warned that the virus may try to delete all files on a local drive on 13 September or 13 March.