Apple Inc. says there is a problem with its latest mobile operating system that is shortening the battery life of iPhones, iPads and iPods that use the software.

Spokeswoman Natalie Harrison said Wednesday that a small number of customers have reported lower-than-expected battery life on devices running on the company's iOS 5 operating system.

She said Apple has found bugs in the program and will release a software update to address them in a few weeks.

The latest iPhone, the 4S, comes with iOS 5.

Other devices can be upgraded to run the software: The iPhone 3GS or 4, iPads and an iPod Touch released in September 2009 or later.

Apple shares added $1.59 to $399 in aftermarket trading. Shares ended the regular session up 41 cents at $397.41.