Battle.net - Blizzard's online service that stores personal and financial data for players of games such as Diablo 3 and World of Warcraft - was recently hacked, the developer confirmed.

"This week, our security team found an unauthorised and illegal access into our internal network here at Blizzard," said Blizzard's president Mike Morhaime. "We quickly took steps to close off this access and began working with law enforcement and security experts to investigate what happened."

"At this time, we've found no evidence that financial information such as credit cards, billing addresses, or real names were compromised. Our investigation is ongoing, but so far nothing suggests that these pieces of information have been accessed."