Media playback is unsupported on your device Media caption The BBC's Richard Taylor was one of the first to out a prototype of "Project Morpheus"

Sony has unveiled a prototype for a virtual reality headset for its PlayStation 4 console at a developers conference in San Francisco.

Shuhei Yoshida, president of Sony's Worldwide Studios, said Sony had been working on the technology - called Project Morpheus - for three years.

"We believe VR will shape the future of games," said Mr Yoshida in a blog post.

The prototype will be made available to developers, but no commercial release date was given.

Project Morpheus is a head-mounted display with 1080p resolution and a 90 degree field of view.

It has sensors built into the unit that can track head orientation and movement, so that when a user's head moves, the image of the virtual reality world moves with it.

Sony's move into virtual reality follows a product released by crowd-sourced group Oculus Rift.

It unveiled its prototype headset Crystal Cove at this year's Consumer Electronics Show in Las Vegas.