The suspect, who was not named, used the pseudonym Topiary and presented himself as a spokesman for the faceless collectives, which have penetrated government and corporate Web sites around the world, the Central e-Crime Unit told the BBC. He is being taken to London while his home is searched.
Police say he was found in an international investigation of cyberattacks on international businesses and spy agencies.
Police said they also are searching a house in Lincolnshire, England, and questioning a 17-year-old boy there.
In its latest action Monday, Anonymous published secret documents stolen from an Italian police cybercrime unit. LulzSec said in June it was disbanding.