Apple has released a fix for the 'Error 53' which permanently shut down iPhones and iPads when the system detected repairs carried out by a non-authorized technician.

The company had faced an outcry after hundreds of users reported earlier this month that their devices were barred from starting up as a result of the software glitch.

Apple initially said that the phones were 'bricked' - or barred - as a "security feature" designed to protect customers.

In an about-turn, it has now released a fix for users affected by the Error 53 and apologised to all those affected.

The issue was apparently caused when a non-Apple technician made repairs affecting the Touch ID, a feature which allows users to unlock their phones with a fingerprint.

Such repairs were normally made as part of fixing a faulty 'home' button on the phone.

Users said when they later tried to run an update, if the phone detected non-standard components it would display the Error 53 message and prevent the phone from being started up again.

A spokesman for Apple told the website TechCrunch that the error was the result of a factory test and was never intended to affect customers.