Apple has released an update for its MacBook and MacBook Pro notebooks, addressing a recently discovered battery performance problem.

According to Apple the notebooks in question were sold worldwide between February 2006 and April 2007. There is no safety issue with the batteries - the issue is limited to performance.

"We have issued a software update that is designed to improve battery performance, and consumers can receive a new battery free of charge if their battery continues to have performance issues after installing the software update, even if their computer is out of warranty," said Apple in a statement.

More information on the battery update is available from Apple's website.