Hackers have managed to break into the Club Nintendo website more than 23,000 times in the past month, Nintendo has confirmed.
Full names, home addresses, phone numbers, and mail addresses were compromised. It was not initially specified whether all Club Nintendo users were affected, but a Nintendo representative has since told CVG: "this only affects the Japanese Club Nintendo and is not an international issue".
As a security measure, Nintendo has reset all Club Nintendo passwords in the region and is emailing users with requests to create new ones.
According to the Wii U manufacturer, the hacking began on June 9 and was detected one month later, on July 2. Nintendo's subsequent investigation found that there were 23,000 unauthorised log-ins from 15 million attempts between those dates.
Nintendo says it is now looking at new measures to strengthen security.
The hack into Nintendo's website is the latest in a string of attacks on publisher websites. On Tuesday, Ubisoft announced that one of its own websites had been compromised. Users were asked to change their uPlay passwords.