Portuguese police arrested seven people today in a concerted attempt to tackle illegal "hacktivism" against the state.

Six men and one woman aged between 17 and 40 were arrested in Lisbon and Porto, the country’s two largest biggest cities, on suspicion of perpetrating distributed-denial-of-service (DDoS) attacks, damaging computers and accessing confidential information illegally.

As part of the swoop the Judicial Police, an equivalent of the British National Crime Agency (NCA), also searched 24 houses and seized dozens of computer systems for forensic analysis.

In a written statement the police said: "The activity of these groups focused on frequent and harmful attacks on institutional, public and private computer systems. The practical consequences of these types of crimes include unexpected inoperability and loss of service.

"This type of crime also has an erosive effect on public confidence in national network structures, damaging its credibility, security and regular operations, and causing larger disruption to information networks, data processing and communication."

Those that have been detained will have to face an initial interview with the Judicial Police, though no charges have yet been announced.