Hackers broke into three websites belonging to the game company and may have stolen the e-mail addresses of up to 25,000 customer registered for product updates and 350 job applicants, according to the BBC.
Square Enix - which makes the Final Fantasy, Deus Ex and Tomb Raider games - has confirmed hackers gained access to parts of its Eidosmontreal.com website and two product sites.
But Square Enix said in a statement that it does not hold any credit card data on its web servers. Square Enix added that here is no evidence the job application information has been distributed, and that the e-mail addresses are not linked to any additional personal information.
The company says it took the sites offline immediately to investigate how the intruders gained access and to increase security measures before allowing the sites to go live again.
Security experts say the latest breaches, like Sony's, could cause problems for those whose data has been stolen, exposing them to e-mail-based scams.
Security in the gaming industry has been in the spotlight in recent weeks since the Sony's PlayStation Network and Sony Online Entertainment multiplayer system were hacked.
Sony has been forced to seek external help to introduce several new security measures. Sony says its improved security measures include increased encryption levels, additional firewalls and an early warning system that will alert the company of any attempts to penetrate the network.
The company is attempting to restore its networks in a phased approach, but the process has been slowed by the high number of password reset request from users.
Sony has announced it will start restoring services in the Americas, Europe, Australia, New Zealand and the Middle East, and hopes to have all regions restored by the end of May.
But authorities in Japan say they will not allow Sony to re-activate its network until the anti-hacking measures it has announced are fully enacted and the company has taken adequate measures to ensure that users' credit card numbers and other private data will not be exposed through its online services again.