Nearly two million computer battery packs have been recalled by Apple after some devices overheated injuring users.

The recall is the second biggest in history involving consumer electronics after a recall by Dell of more than four million of the same lithium-ion batteries last week.

After the Dell recall, consumer safety watchdogs in the United States said it was investigating whether Sony, which makes the batteries, had supplied them to other companies.

The US Consumer Product Safety Commission said today that the recall affects rechargeable, lithium-ion batteries with cells made by Sony Energy Devices, a subsidiary of the Sony Corporation.

They were sold with Apple iBook G4 and PowerBook G4 computers from October 2003 through to this month, according to the commission. Of the 1.8million battery packs recalled around 700,000 were sold outside the United States.

A spokesman for the commission said: "Apple has received nine reports of batteries overheating, including two reports of minor burns from handling overheated computers and other reports of minor property damage. No serious injuries were reported."

In a statement today Sony said that it did not anticipate any further recalls of battery packs with these cells. It has refused to say to which other companies it has supplied the batteries.

After last week’s recall of Dell battery packs, the commission said it knew of 339 examples of the lithium batteries used in laptops and mobile phones overheating between 2003 and 2005.

Apple recalled 128,000 laptop batteries in May last year because they posed a fire hazard. This year it recalled batteries supplied between February 2006 and May 2006 for use with its MacBook Pro laptop.

The lithium-ion batteries contain a liquid that can catch fire if the cell overheats and ruptures. Experts have voiced concerns about the implications if this happened on an aircraft.

The batteries are lighter than their nickel metal hydride predecessors, because they enable more power to be packed into a smaller space. Many of the batteries, however, use cobalt oxide, which experts say can undergo "thermal runaway"; it begins to heat itself, possibly until it catches fire, when it reaches a certain temperature.

The scale of the two recalls is unprecedented. The Dell recall followed the release of internet footage showing an exploding Dell laptop from a conference in Osaka, Japan.

Apple is asking customers to check the following website to determine whether they have a battery subject to the recall, www.support.apple.com/batteryprogram

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