Police confirmed they arrested a 19-year-old man in Wickford, Essex, on suspicion of breaching the Computer Misuse Act. The arrest followed a joint investigation with the FBI.
Scotland Yard would not name the man or say if the arrest was connected to Lulz Security (LulzSec). But the BBC identifies the hacker as Ryan Cleary and the Metropolitan Police's e-crimes unit confirmed the raid was linked to attacks on the websites of the CIA and Britain's Serious Organised Crime Agency (Soca) and intrusions at Sony
Investigators believe Ryan Cleary may have been a significant figure in Lulzsec. But related hacker group Anonymous says Cleary was not the mastermind behind any hacking group, but owned the server LulzSec used to communicate, according to the The Guardian.
On PasteBin, in a posting signed by "LulzSec Security" and addressed to "FBI & other law enforcement clowns", the group details two men's cyber crimes, addresses, aliases, IP addresses, and in one case a phone number and date of birth.
"These goons begged us for mercy after they apologized to us all night for leaking some of our affiliates' logs. There is no mercy on The Lulz Boat. Snitches get stitches," the posting concludes.
Within hours of Cleary's arrest in the UK, the FBI seized web servers in a raid on a datacentre in Reston, Virginia, according to the New York Times.
The paper says a government official - who declined to be named - said the FBI was investigating the Lulzsec group and any affiliated hackers in collaboration with the CIA and cybercrime bureaus in Europe.