Finnish mobile giant Nokia is to install an energy saving device on its phone range that prompts consumers to save otherwise wasted energy.
Nokia said the initiative, which will cause mobile phones to make a sound and display an alert, could save enough electricity to power 85,000 homes annually.
Collaborating with the European Commission, the phone maker is working with other mobile industry firms to reduce energy consumption and pollution.
Mobile phones will display the message 'battery is full, please unplug the charger'.
The alerts will first appear on its 1200, 1208 and 1650 phone models.
Nokia said it would also be targeting fast-growing markets in India, China and Latin America with its energy-saving initiative.
Kirsi Sormunen, vice-president of environmental affairs at Nokia, said: "Around two-thirds of the energy used by a mobile phone is lost when it is unplugged after charging but the charger itself is left in a live socket.
"We want to reduce this waste and are working on reducing to an absolute minimum the amount of energy our chargers use. The new alerts also play an important role, encouraging people to help us in this goal by unplugging their chargers."