The FBI said it was launching a probe into the MyDoom Internet virus that was spreading rapidly and clogging computer networks around the world.
"We are aware of it and we are actively investigating," FBI spokesman Paul Bresson said.
The FBI last year arrested at least two individuals believed responsible for the "Blaster" virus that created havoc on the Internet.
For the new virus, Bresson said, "We have not done a full assessment, but it's serious enough to warrant the FBI to look into this."
More than one million copies of the virus had been intercepted by early on 27 January, according to the security firm MessageLabs, which said the first copies detected were from Russia.
Meanwhile, the apparent target of the virus, Unix operating system owner SCO Group, said it was offering a US$250,000 (AU$325,648) reward for information leading to the arrest and prosecution of the virus creators.
Utah-based SCO confirmed that it was being hit with a distributed Denial-of-Service (DDOS) attack, or bombarded with information requests in an effort to crash its central computers.
"During the past ten months, SCO has been the target of several DDOS attacks," said Darl McBride, president and chief executive.
"This one is different and much more troubling, since it harms not just our company, but also damages the systems and productivity of a large number of other companies and organisations around the world," McBride said.
"The perpetrator of this virus is attacking SCO, but hurting many others at the same time.
"We do not know the origins or reasons for this attack, although we have our suspicions. This is criminal activity and it must be stopped."
SCO said it was working with US law enforcement authorities including the US Secret Service and FBI in the probe.
Ã,© 2003 AFP
