For as long as most people can remember, the name Sony has been identified with high quality, encapsulated in its advertising slogan: "It's a Sony".

So the latest problems with the Japanese group's batteries, used in notebook PCs manufactured by Dell and Apple, come as a big blow.

Last week, Dell recalled 4.1 million notebook computer batteries. That was quickly followed by Apple's recall this week of 1.8 million Sony-made batteries used in its notebooks.

The embarrassing recalls come at a particularly sensitive time for the group and its chairman, Sir Howard Stringer, who is under pressure to turn around Sony's loss-making consumer electronics division and reclaim its position as a pre-eminent brand.

Sony's most-cited problem, openly admitted by insiders, was that it had become bureaucratic and slow-moving and had lost touch with the market.

Sir Howard's stated mission was to break down the silos which prevented the various parts of the Sony group from co-operating with each other and coming up with innovative new products that could bring back the shine to the Sony brand.

But just as things appeared to be looking somewhat better - with television sales growing steadily on the back of its new Bravia LCD TV series and sales of other products also strengthening - the battery issue has raised questions about quality control.

The latest recall is not the only time Sony has had problems with its batteries.

In 1997, Sony recalled alkaline batteries sold at stores due to leakage and in 1999 it recalled lithium-ion batteries used in broadcasting equipment for similar reasons. The following year it also recalled batteries used in its popular Handycam video camcorder - due to leakage - as well as batteries used in Compaq PCs after a battery pack overheated and started emitting smoke.