Signs for watchOS and Mac OS — the Apple Watch and Mac operating systems — hang at WWDC, where updates to both were announced / Getty Images

Apple said that it had found a bug ‘that is taking a bit longer to fix than we expected’, and so would delay the release of the update

Apple will not release its update to the Watch’s operating system, WatchOS 2, after it found a bug during development.

The company said at last week’s Apple event that it would release the update on September 16, along with iOS 9 for iPad and iPhones. But it said that it had “discovered a bug in development of watchOS 2 that is taking a bit longer to fix than we expected”.

“We will not release watchOS 2 today but will shortly,” the company said in a statement to The Independent.

The problems are not thought to impact the release of iOS 9, which is scheduled to come out later today.

WatchOS 2 brought new features including apps that run on the Watch itself, rather than relying on the phone. The company announced it at its WWDC event in June, before detailing new features at last week's event.

Apps that have already been updated for the new OS — which has been available to developers for some time — are also not likely to be removed from the store. Some of those apps have already been submitted to the App Store, as with those that have received updates for iOS 9, though those updates don’t effect the apps when being run on Watch’s that still have the first version of watchOS.