Apple has confirmed that some iPhone 5s units are suffering from battery life issues that cause quicker loss of battery life and longer charging times for a small number of users. If Apple believes your iPhone 5s is affected, it will contact you personally. Read on to find out more. Updated 4 November 2013 with additional replacement information.

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Late in October, Apple spokesperson Teresa Brewer told the New York Times: "We recently discovered a manufacturing issue affecting a very limited number of iPhone 5S devices that could cause the battery life to take longer to charge or result in reduced battery life."

Brewer said that Apple is "reaching out to customers with affected phones," and will "provide them with a replacement phone."

According to 9To5Mac, Apple has told AppleCare representatives that, in addition to shortened battery life and longer charging times, the battery may in fact fail to charge at all.

9To5Mac's report claims that Apple will personally contact customers who have purchased an iPhone 5s with a serial number that matches the affected batch of devices. Customers who believes that they have a faulty iPhone 5s that fits the description of this issue can call AppleCare, which will then enter the serial number of the device into their system to check whether the customer is eligable for a new iPhone.

If your iPhone 5s is among those affected, you'll be able to organise an appointment at Apple's in-store Genius Bar or arrange to get a replacement from an Apple Authorised Reseller.

It's not yet clear how many iPhones are affected by the issue, but NYT suggests that "a few thousand phones" have been affected.

Apple has sold more than nine million iPhone 5s and iPhone 5c units since the new models launched in September, so it's just a fraction of the total iPhone 5s units out there that are affected by the battery life issue.

Find out more about the iPhone 5s in our iPhone 5s review

Other helpful links include:

How to replace an iPhone battery that's not working

How to improve iPhone battery life in iOS 7 and iOS 6