Boffins at Sony have developed an environmentally friendly battery that runs on sugar.

The bio battery works by using enzymes to break down the sugar and create electrical energy.

Tests of the battery showed that it produces 50-milliwatts of energy, which Sony said is enough to power an MP3 player and two speakers.

"Sugar is a naturally occurring energy source produced by plants through photosynthesis," a Sony statement said.

"It is therefore regenerative and can be found in most areas of the Earth, underlining the potential for sugar-based batteries as an ecologically friendly energy device of the future."

The casing for the 1.5in square battery is made from a vegetable-based plastic to make it as environmentally neutral as possible.

The Japanese company plans to produce the batteries commercially, but did not announce a potential launch date.