The online gaming and entertainment services were taken offline on April 20 after a "very sophisticated" attack on Sony's data center in San Diego, said Kaz Hirai, CEO of Sony's games subsidiary, at a Tokyo news conference. They are due to return to service later this week.

Less than two weeks before the most recent attack, Anonymous members launched a denial of service attack against the PlayStation Network in protest at Sony's legal pursuit of hacker George Hotz. Hotz had modified the firmware of a PlayStation 3 so that it could run the Linux OS. Sony claimed the software violated the U.S. Digital Millennium Copyright Act, which prohibits the reverse-engineering of encryption protections.

"While there may be no relation to this attack, the Sony network has also been targeted by the Internet group Anonymous," said Hirai. "In addition, the personal information on Sony's top management, including the names of their children, the schools they attend, and the names of other family members, has been published on the Internet. They have also called for protests outside Sony stores around the world."

"These kinds of cyberattacks may not be limited to Sony. To protect personal information and the safety of the network environment, Sony will cooperate with law enforcement and network security organizations to continuously combat illegal intrusions," said Hirai.

Hirai said the company hadn't been able to find any link between Anonymous and the latest attack.