The FBI said Thursday that it had executed more than 40 search warrants across the US, part of an expanding global probe into the attacks by hacktivist group Anonymous on several companies. The move followed another by British authorities also on Thursday that resulted in the arrests of five suspected participants.

Law enforcement agencies in at least five countries are now conducting their own investigations. The arrests in the UK are the only ones to occur as part of the investigation, although the FBI's move may signal arrests here in the US may not be too far behind.

US law states that participants on denial-of-service attacks can face monetary liabilities and up to ten years in prison.


PayPal -- one of the victims of the attacks -- contacted the FBI in December, and gave the agency information on the IP addresses of the attackers, two of which investigators were able to source to a physical location. That data led to the seizure of a server in Texas.

In an open letter to the UK government, Anonymous called its move to arrest those responsible a mistake. "Not only does it reveal the fact that you do not seem to understand the present-day political and technological reality, we also take this as a serious declaration of war from yourself, the UK government, to us, Anonymous, the people," the group said in a statement.

Officials in the UK are already bracing themselves for attacks on their servers as a result of the arrests. GovCertUK, the government's computer emergency response team, has warned government agencies be vigilant for DDoS attacks, and to report any suspicious activity.