THE HAGUE, Netherlands (AP) — A Dutch citizen has been arrested in Spain in connection with what experts described as the biggest cyberattack in the history of the Internet, one launched against an anti-spam watchdog group last month, prosecutors announced Friday.

The Netherlands National Prosecution Office said a 35-year-old suspect it identified only by his initials, S.K., was arrested Thursday at his home in Barcelona. Authorities also seized computers and mobile phones. Dutch prosecutors do not release full names of suspects, in line with privacy laws.