The launch of Sony's PSP handheld gaming device, described by the company as the "Walkman of the 21st century" and one of its most anticipated products of this year, has slipped and is unlikely to happen outside of Japan until next year.

The company had been planning a worldwide launch of the PSP during the 2004 Christmas season, according to comments made by Ken Kutaragi, executive deputy president of Sony and head of its games unit, during a presentation at an investor conference in New York in November last year.

"To best take advantage of the strong entertainment business unit within the Sony group, I am working closely with Howard (Stringer, chairman and chief executive officer of Sony Corporation of America) to ensure that a wealth of entertainment content will be available at the PSP's launch during the holiday season of 2004 worldwide," he said at the time.

But that's now off the cards, according to Nanako Kato, a spokeswoman for Sony in Tokyo. The company is still aiming for a launch this year in Japan but is now looking to launch the PSP in the US and Europe in 2005.

The reason for the delay is to ensure a wide variety of software is available at the time of the launch of the device, according to Kato.

Sony still plans to unveil a prototype of the PSP at the upcoming Electronic Entertainment Expo (E3) show that due to take place in May in Los Angeles.

A lot of the outstanding questions about the PSP are expected to be answered at E3. To date, Sony hasn't said much about the PSP but what it has said has been enough to have gamers eagerly awaiting the prospect of a small, powerful device that threatens to do for the handheld gaming sector what the company's PlayStation has done for the console market.

Preliminary specifications, announced when Sony first disclosed plans for the PSP at last year's E3, provide a few clues as to what the device is likely to contain.

It will have a 11.4cm, wide-screen TFT (thin-film transistor) LCD (liquid crystal display) with a resolution of 480x272 pixels, 3D (three-dimensional) graphics, support for MPEG4 video and a USB 2.0 port. According to Sony the player will use a new media format called UMD, or Universal Media Disc. The 60mm optical discs will be encased in a cartridge and hold up to 1.8GB of data.

The delay might be good news for Nintendo, which is currently king of the handheld gaming market with its GameBoy range of products. Nintendo has announced plans to launch its own new handheld device, the Nintendo DS, worldwide this year and those plans remain currently unchanged, according to Noriko Takahashi, a spokeswoman for Kyoto-based Nintendo.

Like the PSP, little is known about the Nintendo DS except that it is expected to include more than one processor and possess two TFT LCD panels - the DS stands for 'double screen'. It too is expected to be detailed at the E3 show in May.

For Sony the delay of the PSP comes shortly after it ran into trouble with another high-profile product. The PSX went on sale in Japan over Christmas 2003 with a number of promised features missing.

The company had not managed to complete development of software for the product, which mixes a hard-disk drive based video recorder and a PlayStation 2 games console, in time and was forced to ship products with missing features in order to avoid missing the year-end sales period. Some of those functions have since been added via a firmware update.