Two men have been arrested in Doncaster and Wiltshire in connection with online attacks by hacking gangs Anonymous and LulzSec, Scotland Yard said.
The men, aged 24 and 20, were arrested in Doncaster, South Yorkshire, and Warminster, Wiltshire, for conspiring to commit offences under the Computer Misuse Act 1990.
Scotland Yard said the arrests were part of a continuing investigation in collaboration with the FBI, South Yorkshire Police and other law enforcement bodies, into activities of Anonymous and LulzSec, especially in connection with suspected offences under the cover of online identity "Kayla".
A spokesman said the men were arrested separately at addresses in Mexborough, near Doncaster, and Warminster. He said the Doncaster address was searched by police and computer equipment was removed for forensic examination. The men have been detained at police stations in South Yorkshire and central London.
Detective Inspector Mark Raymond from the Metropolitan Police's Central e-Crime Unit (PCeU), said: "The arrests relate to our inquiries into a series of serious computer intrusions and online denial-of-service attacks recently suffered by a number of multi-national companies, public institutions and government and law enforcement agencies in Great Britain and the United States.
"We are working to detect and bring before the courts those responsible for these offences, to disrupt such groups, and to deter others thinking of participating in this type of criminal activity."
In a separate but similar investigation into hacking two men were today charged over online attacks by international hacking gang Anonymous, Scotland Yard said.
Christopher Weatherhead, 20, from Northampton, and Ashley Rhodes, 26, from Kennington, south London, have been charged with conspiracy to carry out an unauthorised act in relation to a computer.
All four will appear on bail at City of Westminster Magistrates' Court on September 7.