Sony Xperia Z5 Premium phone boasts a 4K display

Sony has announced a new phone, which it says is the first to feature a 4K screen.

It means the handset can display videos at four times the quality of 1080p high definition.

The Xperia Z5 Premium can also upscale existing video clips from Netflix, YouTube and elsewhere to take advantage of the innovation, but analysts warn that doing so will have an impact on its battery life.

Sony's smartphone unit is currently run at a loss, but the firm hopes to turn its fortunes around by the end of its next financial year.