The issue was caused by an earlier update to its iOS 8 mobile operating system released on Wednesday and the tech giant had scrambled to fix the glitch, releasing an update late yesterday that it claimed would resolve the issue.

Apple has also had to defend its iPhone 6 Plus against social media reports that its extra-large shell is vulnerable to bending, saying bending "is extremely rare" with normal use of an iPhone and that just nine customers had contacted the company to report a bent iPhone 6 Plus since they went on sale despite a record 10 million sales of the new models in the first weekend.

But the firm was contrite about the iOS issue, having previously vowed to work "around the clock" to fix it, saying: "We apologise for inconveniencing the iPhone 6 and iPhone 6 Plus users who were impacted by the bug in iOS 8.0.1.”

The company reported this week that nearly half of all iPhone and iPad users had upgraded...