Three suspected members of the Anonymous hacking group have been arrested in Spain.
The trio are said to have been involved in co-ordinating the group's activity in that country.
The arrests were made simultaneously in three Spanish cities - Barcelona, Valencia and Almeria.
Anonymous has claimed responsibility for attacks on Sony, Spanish banks and co-ordinated action in defence of whistle-blowing site Wikileaks.
A statement from the Spanish national police force said that a computer seized in the home of one person it arrested was used in the hacks.
The arrests were the culmination of an investigation that began in October 2010.
It involved Spanish cyber police combing through millions of lines of chat logs to identify who was behind the group's activities.
Some of the attacks made by Anonymous members used a web-based tool called Loic to bombard target sites with data. The websites of PayPal, Mastercard and Amazon were all targeted using this tool.
It seems that Loic did a poor job of hiding the identity of the people using it. It is believed that some police forces have already moved against the group based on this information.
Arrests have been made in the US, UK and Holland of Anonymous members, prior to the raids in Spain.
Anonymous grew out of the online picture sharing site 4Chan and describes itself as a group of concerned internet citizens.
As well as attacking sites that it perceives as not supporting Wikileaks, the loosely organised collective has also attacked government sites in Tunisia and Egypt to aid popular protest movements.