REUTERS/Robert Galbraith

Apple Inc CEO Tim Cook speaks on stage during an Apple event in San Francisco, California October 22, 2013.

Days after a leak of celebrity photos exposed a vulnerability in iCloud, Apple has updated its developer guidelines to warn app developers that the health data of users can't be stored using the company's own online storage service.

9to5Mac reports that amongst the changes to the App Store Review Guidelines is an additional rule barring developers from storing HealthKit data in iCloud.

The new line added yesterday to Apple's guidelines makes it completely clear that iCloud is a no-go for the health data of users:

"Apps using the HealthKit framework that store users’ health information in iCloud will be rejected."

The Apple review guidelines are used to inform app developers of what is and isn't allowed in the App Store, with Apple making it clear that it will reject any apps that breach their guidelines.

Apple unveiled its HealthKit app in June during its WWDC event. The app brings together the health data of users, gathered using apps and wearable devices that monitor things like blood pressure and calorie intake. The unified app means that all of a user's health data is in one place, making it a clear target for hackers. But on its website, Apple is clear on how secure the data is stored, saying "A user’s health information is stored in a centralized and secure location."

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