Apple is to replace faulty batteries in some iPhone 6s handsets that cause the smartphone to "unexpectedly shut down", the technology giant has said.

The iPhone maker is asking any users of the 6s who have encountered the issue to visit an Apple Store or one of the company's official service providers to have their battery examined, with replacements provided for free if found to be eligible.

Apple said in a statement the fault was not a safety issue and only affected a "very small number" of iPhone handsets.

"Apple has determined that a very small number of iPhone6s devices may unexpectedly shut down. This is not a safety issue and only affects devices within a limited serial number range that were manufactured between September and October 2015, " the company's statement said.

"If you have experienced this issue, please visit an Apple Retail Store or an Apple Authorized Service Provider and have your device's serial number checked to confirm eligibility for a battery replacement, free of charge."

Apple warned users that any iPhone handsets found to be eligible would need to have any cracked screens repaired before the firm could go ahead with the battery replacement.

The announcement comes just weeks after Samsung was forced to recall and then discontinue their Note7 smartphone after multiple incidents of devices catching fire and exploding.

The issue that was initially linked to battery manufacturing, but the Korean firm is still investigating to determine the cause.

The iPhone 6s was launched in September 2015 and was the first iPhone to feature a pressure sensitive screen, known as 3D Touch.

The battery replacement comes just days after Apple announced a similar scheme to fix a fault in their iPhone 6 Plus that causes the screen to become less responsive over time - an issue known as "touch disease". However that fix comes with a service price of £146.

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