Washington, July 25 - Fake Internet postcards circulated through electronic mails worldwide carry links to a deadly virus known as Zeus Bot, according to a new study.

Gary Warner, computer forensics director at the University of Alabama at Birmingham (UAB), who led the study, said, Zeus Bot has been named America's most pervasive computer virus, reportedly affecting some 3.6 million computers in the US.

'These fake postcards ask users to click and download to view the contents, and as soon as they do so, the Zeus Bot infects their computers,' Warner said.

Once on a computer, Zeus Bot will give cyber criminals access to passwords and account numbers of banks and other sensitive online accounts.

Warner said cyber criminals who are employing the Russian-language Zeus Bot software are using the fake Internet postcards as the latest mechanism to download the virus software onto unaware users' computers.