Apple denies that any of its databases were hacked in relation to this weekend's celebrity photo dump.

Apple said of the hacks: "After more than 40 hours of investigation, we have discovered that certain celebrity accounts were compromised by a very targeted attack on user names, passwords and security questions, a practice that has become all too common on the internet."

"None of the cases we have investigated has resulted from any breach in any of Apple's systems including iCloud or Find My iPhone."

Both the FBI and Apple are investigating the hack, which resulted in the release of 100's of nude photos of celebs.

Apple's statements would appear to back the theory that the hacks were not the result of a sophisticated infiltration of the iCloud system, but rather a targeted attack that used guessed password-recovery questions or a "brute force" attack, in which thousands of potential passwords are entered via an automated tool.

Again, Apple is stressing that users create strong passwords.