The devices have up to one gigabyte of storage

The devices are pitched into a competitive market recently swelled by the addition of Apple's iPod shuffle.

Unlike hard disk-based players, flash devices hold fewer songs, using solid state memory rather than a disk.

The Sony line-up includes MP3 players which hold a similar number of songs to the iPod shuffle - about 250 - but the players have much longer battery life.

The new players have up to one gigabyte of storage and depending on which version, cost between $150 and $180.

Sony said the new devices would have 50 hours of battery life - compared to the Shuffle's 12 - and they also come with a small display screen.

Apple has made much of the fact its Shuffle does not have a display, and has marketed the random playback of its device as a selling point.

Sony admitted it had to recover ground in the digital music player market.

"We know we've been behind a bit," said Kelly Davis, a Sony product manager for digital players.

"But we definitely want to be a strong contender in 2005."

Industry analysts have welcomed the new models and predict Sony will make an impact.

"It's like the empire strikes back," said Richard Doherty of The Envisioneering Group.