The virus, which the company named "Storm Worm" is sent to hundreds of thousands of email addresses globally, with the e-mail's subject line saying "230 dead as storm batters Europe."

The attached file contains the so-called malware that can infiltrate computer systems.

"What makes this exceptional is the timely nature of the attack," Mikko Hypponen, head of research at F-Secure said.

Hypponen said thousands of computers around the world, most in private use, had been affected.

He said most users would not notice the malware, or trojan, which creates a back door to the computer that can be exploited later to steal data or to use the computer to post spam.