The cheaper of Sony's two PlayStation 3 (PS3) consoles is getting harder to find in the US.

The 20GB version, which costs $500, has been taken off-sale by retailer BestBuy and Sony's own online store displays an error message when the page for the model in question is requested.

But despite its removal from SonyStyle the product hasn't been discontinued, the company said.

"The line-up [at SonyStyle] is decided based on market demand and so it's not surprising that they are not selling it on their website but if you go to a retailer you can find it," said Satoshi Fukuoka, a spokesman for Sony in Tokyo.

He said the more expensive PS3 with a 60GB hard-disk drive has always been more popular among users and that's why some retail outlets aren't stocking the lower-spec model. The second version costs $600 and comes with a wireless internet adapter not present on the cheaper model. In the UK, Sony is only selling the 60GB PS3.

A possible new version of the PS3 was revealed last month in a filing made by Sony to the US Federal Communications Commission. In the filing Sony noted a new model with an 80GB hard-disk drive.

A spokesman for Sony declined to comment on the company's plans for future upgrades to the PS3.