Apple has begun a recall of 1.8 million notebook batteries following concerns of a possible fire risk. 

The defective batteries were sold between October 2003 and August 2006 with Apple's 12in iBook G4, 12in PowerBook G4 and 15in PowerBook G4 computers.

The company said that it is aware of nine cases of overheating batteries leading to property damage or minor burns. No serious injuries have been reported.

Apple urged users to stop using the batteries and to contact Apple customer service. The vendor will replace the batteries free of charge. 

About 1.1 million of the battery packs are in use in the US, and the remaining 700,000 were sold internationally.

The batteries were manufactured by Sony which also supplied the 4.1 million batteries that Dell was forced to recall last week. 

Apple's recall is the second largest involving electronics goods after Dell's.

The Dell recall followed on the publication of photos of a laptop catching fire in Kyoto, which prompted numerous consumers to come forward claiming that their notebooks had fallen victim to overheating batteries. 

Dell has always denied a link between the online reports and its recall. But the company has admitted that it knew about the underlying production problems as early as last October. 

Both the Dell and Apple problems were caused by tiny pieces of metal floating inside the battery, Sony said in a press release.

When the batteries are being used or recharged, the battery will heat up and these particles can start moving around, potentially causing the unit to short circuit. This can cause the battery to explode or catch fire.

Sony added that it does not expect any additional recalls of battery packs.