Antivirus company says Klez worm is No. 1

Klez.h, the voracious variant of the Klez worm, not only stole the crown for "most widely spread virus" but also accounted for more than 96 percent of all reports of virus attacks in the month of May, Moscow-based antivirus company Kaspersky Labs said on Monday. CIH and Elkern, two other viruses that have been found piggybacking on the Klez virus, have together made up another 1 percent.

Data on the Web site of U.K.-based mail service provider MessageLabs indicates that Klez has surpassed SirCam as the most prolific virus. The company has intercepted more than 767,000 copies of SirCam and has caught almost 908,000 copies of Klez.