Apple is offering free battery replacements on some of its iPhone 6s devices after discovering a defect that causes the phones to unexpectedly shut down.

In a support page on its website, the company said the free repair programme aims to address the fault in a very small number of its iPhone 6s devices.

The concerned consumers are urged to contact Apple online, visit an Apple store or authorised service provider to learn whether their device is eligible for a fix. Wireless carrier partners are not taking part in the programme.

The defect affects devices within a limited serial number range that were manufactured between September and October 2015, and the company assured customers that there is no safety issue.

The company said if user’s iPhone 6s has any damage like a cracked screen which impairs the battery replacement, that issue should be resolved before the battery replacement. In several cases, users will be charged for the cost associated with the repair.

iphoneApple said it could restrict or limit repair to the original country of purchase and the replacement programme does not extend the iPhone 6s’ standard warranty coverage.

The programme covers affected iPhone 6s batteries for three years after the unit’s first retail sale.

Apple’s replacement plan comes two months after Samsung Electronics moved to replace millions of its Galaxy Note 7 phones due to battery explosion.

The South Korean firm recalled its Note7 phones in September after 35 cases of the device overheating or catching fire were reported.