If you've noticed that your iPhone 5S battery is quick to drain and slow to charge, you could be the owner of one of "a very limited number" of handsets that has a battery defect.

Apple has conceded that some of the new iPhones have a problem with their batteries, although it's not saying how many are affected beyond "a very limited number".

The company's spokeswoman, Teresa Brewer, told the NYT, "We recently discovered a manufacturing issue affecting a very limited number of iPhone 5S devices that could cause the battery to take longer to charge or result in reduced battery life."

Circle back

Apple is "reaching out" (contacting) those with affected phones to provide replacement handsets.

In our full TechRadar iPhone 5S review, we deemed the battery to be a little better than that of the iPhone 5's - specifically when it comes to standby life. However, actually using the handset still gulps that juice down like a hyperactive toddler on a hot day.

There's good news for non-defective iPhone 5S handsets though: "The iPhone 5S charges phenomenally quickly." Phenomenally.