Apple is now offering to replace batteries for the iPhone 6S, if users find that their devices are abruptly shutting down.

This is its second global repair offer, just days after the last one for the iPhone 6 Plus's screen issue.

"Apple has determined that a very small number of iPhone 6S 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," Apple said in a statement.

The program is applicable globally. Users can visit authorized Apple service centres and get the serial number checked, to confirm if their iPhone 6S is affected or not.

Apple requests users to take a backup of their iPhone 6S, turn off the "Find my iPhone" service and erase the phone before handing it over.

There's one caveat though. If your iPhone 6S has a cracked display or any other damage, you will have to get that repaired before getting the battery replaced, which could incur some additional cost.

Users who have already got their iPhone 6s' battery replaced can reach out to Apple for a refund.