Apple has announced a software update and a voluntary recall programme for batteries in its MacBook and MacBook Pro laptops. 

The issues do not present a safety risk, and Apple said that users can continue to use affected batteries.

The problems affect certain laptops sold between February 2006 and April 2007. Separate extra batteries shipped during the same period are also affected.

Apple issued the update after finding that some battery packs were not charging, or were charging to a low capacity. Some were not being recognised by the laptops, while some were found to be deformed.

The software update is available through the Mac OS X software update utility or from Apple's website. If the update does not fix the problem, the company will replace the affected battery packs for free.

Apple also announced that it will extend repair coverage support for Intel Core Duo-based laptops for an additional two years.

Last summer, Apple recalled 1.8 million Sony batteries in its iBook and Powerbook models that were deemed potential fire hazards.