British police arrested a 19-year-old man in a remote Scottish archipelago on Wednesday on suspicion of being a spokesman for the Lulz Security and Anonymous computer hacking groups, Scotland Yard said.
Officers from a London-based cyber crime unit detained the man in a "pre-planned intelligence-led operation" on the Shetland Islands, off the northeast coast of Scotland, London's Metropolitan Police said in a statement.
"The man arrested is believed to be linked to an ongoing international investigation into the criminal activity of the so-called 'hacktivist' groups Anonymous and LulzSec, and uses the online nickname 'Topiary' which is presented as the spokesperson for the groups," the statement said.
He was being transported to a London police station and a search was under way at his house, it said.
Police are also searching a residential address in Lincolnshire, eastern England, and a 17-year-old male was being interviewed in connection with the inquiry although he had not been arrested, police said.
Lulz Security has claimed responsibility for a hacking rampage in the United States which saw the group target websites of the Central Intelligence Agency, the US Senate, Sony and others.
Last week, Rupert Murdoch's British newspaper division News International pulled its websites after LulzSec replaced the online version of daily tabloid Sun with a fake story pronouncing the mogul's death.
Anonymous gained prominence after launching retaliatory attacks on companies perceived to be enemies of the whistle-blowing website WikiLeaks.
Anonymous and Lulz Security called in a joint statement Wednesday for a boycott of micropayment site PayPal to punish the electronic payments firm for its refusal to accept donations for WikiLeaks.
Scotland Yard said Wednesday's operation was linked to the cybercrime unit's "ongoing investigation into network intrusions and Distributed Denial of Service (DDoS) attacks against a number of international business and intelligence agencies by what is believed to be the same hacking group," said police.
DDoS attacks overwhelm websites with requests, causing them to slow down or be inaccessible.
Authorities in Britain and the United States have already made a number of arrests of suspected Lulz Security and Anonymous hackers.
British police arrested Ryan Cleary, 19, last month at his home in Wickford, southeast England, and charged him with attacking websites as part of Lulz Security.
He was charged with offences including hacking into the website of the Serious Organised Crime Agency (SOCA), the British equivalent of the FBI. He was released on bail after being diagnosed with autism.
US authorities on July 19 arrested 16 people for cyber crimes including 14 over an online attack on the PayPal website claimed by the hacking group "Anonymous," the Department of Justice (DoJ) said.
In a sign of the transnational nature of the two hacking groups, it said those raids were carried out in coordination with Scotland Yard and the Dutch National Police Agency.