A new scheme rating the environmental impact of different mobile phones has been launched by communications giant O2.

The eco-rating system is based on the overall environmental impact of a device over its lifespan, the raw materials it contains, its packaging, energy efficiency and how easy it is to recycle.

The Sony Ericsson Elm topped a list of 65 models from six manufacturers, according to the report.

Ronan Dunne, O2's UK chief executive, said: "We know that sustainability is important for many of our customers and for the first time they will have the whole picture from which to make a full and balanced purchasing decision.

"Consumers are becoming increasingly aware of the social and environmental impact of the technology they buy and we believe this kind of product transparency will help empower them to make greener choices."