Sega said that encrypted user passwords were viewed in the attack. (KIM KYUNG-HOON/REUTERS)

The company said that accounts from its Sega Pass online network were compromised, and hackers accessed user names, birth dates and passwords. Credit card numbers were not accessed in the attack.

The company said its Sega Europe division immediately notified Sega and its customers of the attack after learning about it Thursday night.

Sega said that user passwords were encrypted. It’s not clear how long the network will be down. On the company’s Web site, a message says the network is “going through some improvements” and is currently unavailable for new users to register or existing users to modify account details such as passwords.

LulzSec, the hacker group that has claimed responsibility for attacks on organizations including the CIA and U.S. Senate, and other game companies including Bethesda Softworks, Nintendo and Sony, said that it was not responsible for the attack on Sega and offered to help track the perpetrators down.

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