Update: Turkish security researcher Ibrahim Balic claims that he was behind the "hack" but insisted that his intention was to demonstrate that Apple's system was leaking user information, not cause any harm or steal sensitive information. His findings were submitted to Apple and details were posted to YouTube – though the video has since been pulled. Apple took its developer site offline shortly after Balic sent in his report and has not been in contact with the researcher. Original story follows below.

Apple's developer website has been unavailable for the best part of four days, with the company revealing just today the cause of the extended downtime. In an email sent to developers, Apple explains that an "intruder" had accessed the developer portal in attempt to steal personal information from its users, and that although sensitive information was encrypted so it couldn't be accessed, the intruder may have accessed email addresses, mailing addresses and names.

Since Apple discovered the issue last Thursday, the company immediately shut down the website and began work "around the clock". The company is "completely overhauling [their] developer systems" as well as updating server software and rebuilding databases to ensure that a security threat such as this can't happen in the future. Additionally, company spokesperson Tom Neumayr told AllThingsD that "the website that was breached is not associated with any customer information".

The developer site forms a very important part of Apple's relations with app developers, as it allows access to various copies of development kits such as the iOS 7 beta. When the site originally went down on Thursday a notice was posted saying the site was down for maintenance, although now an updated message informs all developers of the cause of the maintenance while still preventing any access.

Meanwhile, a number of developers registered with the site have been reporting numerous password reset emails appearing in their inboxes, asking them to head to the Apple developer portal to change their password. With Apple revealing the security issue with the website, it's not surprising that these emails are being sent, and most importantly they should be ignored until the issue has been resolved.