Sony Ericsson has announced the launch of four new phones today including a new Walkman branded model and a phone aimed at the fitness set.

The new Walkman phone comes in the quise of the W850i and is the first GSM/3G "slider" in the range.

It will sport a 2-inch QVGA 260k colour screen and a 2 megapixel camera with 4x digital zoom.

On the music side, the phone will come with a 1GB MS Pro Duo card enough for approximately 1000 tracks and the Walkman player supports MP3, AAC, AAC+ eAAC+ and M4a playback.

The phone also promises up to 30 hours playback. Connectivity is in the form of 3G and Bluetooth.

Designed to support an active, sporty lifestyle, the other Walkman phone launched today is the W710i, which includes a motion sensor plus new fitness applications that measure your running speed, distance and time, or simply count your steps when walking.

The other two phones launched are both apart of Sony Ericsson's Z range of handsets.

The Z550i is finished in a combination of brushed metal and high gloss material, the Z550i will feature a 1.3 megapixel camera has 4x digital zoom as well as 20MB user memory expandable upto 1Gb via Memory Stick Micro. Triband, Bluetooth and a 262k colour screen complete the offering.

Z710i will be EDGE-capable, come in a clamshell design and sports a 2 megapixel digital camera, a surprisingly low 10MB user memory and bundled 64MB memory Stick Micro card. It has a 1.5-inch 262k colour screen. The Z710 is a Quad-band EDGE/GPRS phone available in Twilight Black or Metallic Sand and starts shipping during Q3 2006.