Most of the websites affected by the online attacks that followed Thursday's shutdown of the Megaupload file-sharing site were back online early Friday, including the Department of Justice, the RIAA, the MPAA, BMI and Warner Music Group.
The "Hacktivist" collective Anonymous claimed credit for Thursday's attack. A law enforcement official told CNN the FBI was investigating the incidents.
Reps for Warner Music and Universal Music Group, the latter of which was still down at press time, declined to comment on the situation when contacted by Billboard.biz late Thursday, but the MPAA issued the following statement:
"Our website and many others, including the Department of Justice, were attacked today and the hacker group Anonymous is claiming responsibility for the attacks. We are working with law enforcement authorities to identify those responsible.
"Unfortunately, some groups believe that speech or ideas that they disagree with should be silenced. This could not be more wrong. No matter the point of view, everyone has a right to be heard.
"The motion picture and television industry has always been a strong supporter of free speech. We strongly condemn any attempts to silence any groups or individuals.
"The Internet is home to creativity, innovation and free speech. We want to keep it that way. Protecting copyrights and protecting free speech go hand in hand."
Megaupload founder Kim "Dotcom" Schmitz and three other men arrested in connection with the charges appeared in court in New Zealand on Friday and will remain in custody until at least Monday, when their bail applications will be considered. Lawyers acting for the United States government were opposed to bail for the defendants.