Game company Sega confirmed that data from 1.3m customers was stolen by hackers from its Sega Pass online membership network.
According to Reuters, names, birth dates, email addresses and encrypted passwords were compromised, though credit card numbers were safe.
"We are deeply sorry for causing trouble to our customers. We want to work on strengthening security," said Yoko Nagasawa, a Sega spokesperson.
Sega also took down the membership network, with no date given for when it will return.
The hack is the latest in tech security breaches, with the most notable coming from the hack of the PlayStation Network, Qriocity and Sony Online Entertainment, which affected 100m users.
However, the group claims it is not behind the Sega attack and has even offered to help the company “destroy” the Sega Pass hackers as LulzSec says its members are fans of Sega’s last games console, the Dreamcast.