A solar-powered mobile phone that can be entirely operated by exposure to sunlight is to be launched this summer in Japan.

The new phone is a waterproof, sunlight-powered device which will be sold by the Japanese mobile phone company KDDI from June.

Ten minutes of explosure to sunlight is sufficient for a one minute call or to power the handset in standby mode for two hours.

As much as 80 per cent of the battery of the handset, a collaboration with manufacturers Sharp Corp, can be recharged entirely by sunlight as a result of storage technology embedded in the front face of the phone, according to manufacturers.

Marketed as a "green" eco-friendly alternative to conventional mobile phone handsets, the company claims that the device's lack of dependence on standard electricity will help reduce carbon dioxide emission levels.

The new handset is the latest in an increasingly competitive global race among mobile phone companies to produce "eco friendly" devices.

Two months ago, the Korean company Samsung Electronics unveiled a solar-powered mobile phone made from recycled plastic from water bottles.

While the company claimed it was the world's first solar-powered mobile phone device, it did not state when it would go on sale.

Meanwhile, in January, Motorola described its new W233 Renew, also made from recycled water bottles, as the world's first carbon neutral mobile phone.

A solar-powered mobile phone that can be entirely operated by exposure to sunlight is to be launched this summer in Japan.