Apple has admitted that there is a fault with some of its batteries in its MacBook and MacBook Pro laptop lines.

In response to the problem, Apple has released a battery update that updates the battery firmware and improves battery functionality.

The update affects most Intel-based laptops and was released because the Californian company had identified an issue that was causing poor 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.

"The factors causing the performance issues do not present a safety risk. You may continue to use your current battery", the company said.

The company advises users to install the update on all "MacBook and MacBook Pro computers and extra batteries that were purchased between February 2006 and April 2007".

Last year laptop users were heavily effected by battery recalls from most manufacturers following a batch of over 9 million faulty batteries being supplied by Sony.