Arrest of suspected hacker "significant" - police

WICKFORD, England (Reuters) - Britain's top policeman said Wednesday the arrest of a suspected teenage hacker was "very significant" in the international hunt for a group suspected of carrying out cyber attacks on global companies and law enforcement agencies.

The 19-year-old was held by London's Metropolitan Police on Tuesday as part of a joint investigation with the U.S. FBI into recent attacks on high profile websites.

However, an undercover group which claims responsibility for attacks on the U.S. Central Intelligence Agency (CIA), Britain's Serious Organised Crime Agency (SOCA), and Sony Corp rejected suggestions the teen-ager was a leading figure.

British media have named him as Ryan Cleary, who lives with his mother in an unassuming house in Wickford, a quiet suburban town to the northeast of London.

The detached house had all the curtains drawn and a sign on the door reading: "To all concerned, please do not knock for an interview as I'm unable to comment."

Police said Wednesday the teen-ager remained in custody where he was being questioned on suspicion of Computer Misuse Act and Fraud Act offences.

"It's a very significant arrest," Metropolitan Police Commissioner Paul Stephenson said without elaborating. "The challenges around cyber crime are extraordinarily significant and deeply worrying."

Cleary's mother Rita, 44, told the Daily Mail newspaper her son suffered from agoraphobia and attention deficit disorder. She said he had not left his home for four years, and barely left his room.

"He is incredibly intelligent but he had very complex needs," the paper quoted her as saying.

The Lulz Security (LulzSec) group of hackers, which says it has hacked into the websites of the CIA, SOCA and Sony, have distanced themselves from Cleary and dismissed suggestions he was the group's mastermind.

"Clearly the UK police are so desperate to catch us that they've gone and arrested someone who is, at best, mildly associated with us. Lame," the group said on its Twitter website.

"Ryan Cleary is not part of LulzSec; we house one of our many legitimate chatrooms on his IRC server, but that's it."

Members of LulzSec, which often uses so-called denial-of-service attacks to overwhelm websites with internet traffic, are believed to be scattered around the world collaborating via secret chatrooms.

Security experts say the group emerged from Anonymous, a hacker activist group which became well-known for targeting companies and institutions that opposed WikiLeaks and its founder Julian Assange.

Hackers have also targeted the International Monetary Fund, Lockheed Martin Corp, Citigroup Inc, and Google in recent serious security breaches although no group has claimed responsibility for those attacks.

(Additional reporting by Michael Holden and William Maclean; Editing by Jodie Ginsberg and Philippa Fletcher)