Apple said on Friday some batteries in its MacBook and MacBook Pro notebook computers may have performance problems, but they do not pose a safety risk.

Apple said problems with affected batteries include not charging when the computer is plugged into an outlet.

"The issues are not a safety risk, so consumers can continue using their batteries," the company said in a statement.

The affected batteries are in MacBook and MacBook Pro notebooks sold worldwide from February 2006 and April 2007, Apple said.

Apple said it has issued a software update designed to improve battery performance. Those who bought the notebook with the batteries in question can get a new, free battery if it continues not to perform. The replacement program also applies if the computer is out of warranty.

Apple said it does not expect the battery update to have a material impact on earnings.

More information about the update and battery replacement program may be found on the Internet at http://www.apple.com/support/macbook_macbookpro/batteryupdate/.