Apple has responded to reports that its iCloud storage service was breached when hackers stole hundreds of explicit images of celebrities including Jennifer Lawrence, Kirsten Dunst and Kate Upton.

iCloudApple denies iCloud is to blame for the celebrity picture hack [Getty/Justin Sullivan]

Though Apple are ambiguous on whether the photos were stored on the iCloud service, it denies that the hack was part of a large scale security breach and instead suggests the celebrities had usernames, passwords and security questions compromised. 

iCloud was immediately the focus of attention into the how the photos were stolen and many 4chan users - the website on which the pictures were uploaded - noted that the majority of pictures were taken on iPhones.  

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In its statement, Apple said it was "outraged" by the theft and spent 40 hours investigating it having "mobilized" its engineers. 

"We wanted to provide an update to our investigation into the theft of photos of certain celebrities. When we learned of the theft, we were outraged and immediately mobilized Apple's engineers to discover the source. Our customers' privacy and security are of utmost importance to us. 

Kate UptonNaked pictures of Kate Upton leaked online [Getty/Jason Kempin]

"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. We are continuing to work with law enforcement to help identify the criminals involved."

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The FBI is currently investigating the stolen photos, though it now appears those responsible could be part of a larger ring of hackers. It is believed that more images and videos could be on the way.