MUMBAI: The fight over the controversial Stop Online Piracy Act (SOPA) anti-piracy bill is leading to aggression and battle all over the web world.

On 19 January, the US Department of Justice and FBI announced that they were shutting down file-sharing site' Megaupload.com' over piracy violations. They charged the site's founders and five others with internet piracy crimes for running an international organized criminal enterprise.

Just few minutes later,  an informal hacking group called â€?Anonymous' took down six prominent government agency websites including US Department of Justice, Universal Music Group, the Recording Industry Association of America (RIAA), the Motion Picture Association of America (MPAA), the US Copyright Office and the Utah Chiefs of Police Association. The group also hacked the FBI's website for a certain time but now it is retrieved.

The government takes down #Megaupload? 15 minutes later #Anonymous takes down government & record label sites,... they wrote on Twitter.

The account, under the name @YourAnonNews identifies itself on Twitter as the infamous hacker collective, saying "We are Anonymous, We are legion, We never forgive, We never forget, Expect us."

Anonnews also now calls the operation the largest ever that Anonymous has undertaken in terms of participants, with 5,635 computers running the distributed attack software that the hacker group uses.

The activists are angry about two proposed antipiracy bills backed by the music and movie industries, SOPA and PIPA, that critics say would give authorities broad power to shut down Web sites for the mere accusation that they had pirated content on them.

At the time of filing the story the US Copyright Office, MPAA was up, but RIAA, UMG still struggled to get back the site.