Supporters and users of sites hosting pirated movies and music launched a denial-of-service (DOS) attack against the websites of the film and music industry temporarily knocking the latter's sites offline.

The attacks against the sites of the Motion Picture Association of America (MPAA) and the Recording Industry Association of America (RIAA) were declared on the Internet forum 4chan.

The piracy activists claiming responsibility for the attacks said their action was in retaliation for the same attack on The Pirate Bay with the MPAA and RIAA hiring Aiplex, an Indian software firm, to flood the file-sharing website's with messages.

Aiplex had admitted to the Australian newspaper Sydney Morning Herald that it conducted the DOS attack against The Pirate Bay on behalf of the MPAA and RIAA. It also confirmed to BBC the attack on its website that took it offline for a day and a half.

The anonymous piracy activists, who called their action "Operation Payback," said they also attacked Aiplex's website and the British Phonographic Industry.

Meanwhile, an anonymous group temporarily knocked Australian government websites offline in protest to the plan of authorities in that country to introduce net filters.