British police on Thursday arrested two men as part of a trans-Atlantic investigation into attacks carried out by the hacking groups Anonymous and Lulz Security.

Scotland Yard said a 24-year-old and a 20-year-old were arrested at two separate U.K. addresses as part of a continuing investigation in collaboration with the FBI and other law-enforcement agencies.

"The arrests relate to our enquiries 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," said Detective Inspector Mark Raymond from the Metropolitan Police's Central e-Crime Unit.

Hacking group Lulz Security has claimed responsibility for attacks on targets such as Sony Corp., the CIA and Britain's Serious Organized Crime Agency.

The group is a spin-off of Anonymous, an amorphous group of activists, hackers and prankster whose targets have included Visa and MasterCard.

Anonymous cut its teeth with attacks on the music industry and the Church of Scientology but has lately turned its focus to law enforcement, intelligence and military-related sites.

Police said the two men arrested Thursday remain in custody and a computer seized in the investigation is being examined.

The arrests come amid a trans-Atlantic crackdown on Anonymous and its supporters. Dozens of arrests linked to the ad hoc international hacking collective have been made in recent weeks, including a cross-country FBI sting earlier this summer in which 14 alleged cybercriminals were arrested.

Earlier Thursday, British police said two more men have been charged in relation to denial-of-service attacks carried out by Anonymous.

The charges against Christopher Jan Weatherhed, 20, and Ashley Rhodes, 26, are considered part of a separate from the joint FBI investigation.

Weatherhed and Rhodes will appear at City of Westminster Magistrates Court on Sept. 7 alongside two others previously charged with the same offense.

Denial-of-service attacks choke websites with traffic the same way a telephone line might be jammed with thousands of crank calls.

Anonymous likens such attacks to online civil disobedience, but penalties can be severe. The maximum sentence for a conviction on such a charge is 10 years in prison.

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Raphael G. Satter contributed to this report.