Mayor Ken Livingstone has proposed ambitious new targets for reducing carbon emissions in London.

Announcing a review of the 'London plan' development strategy, he said a series of new building, transport and energy policies aim to cut carbon dioxide by 20 per cent by 2015, and by 60 per cent by 2050.

Planners and developers will be required to connect new buildings to decentralised local energy supplies, meet high sustainable building standards and achieve a 20 per cent emissions reduction using onsite renewable energy.

A decentralised energy system is one where electricity is created close to where it is needed, through devices on buildings, like solar panels or wind turbines, and using combined heat and power boilers.

Livingstone said: "The new policies I am publishing today set tough but deliverable targets for reducing our carbon emissions.

"We must move our cities away from relying on inefficient centralised heat and power generation, and stop constructing buildings that waste heat and electricity.

"In London we want to see the widespread use of decentralised energy, the highest standards of green building design and renewable energy incorporated wherever we can."

The proposed alterations to the London plan will go to the London assembly and the Greater London Authority before public consultation this autumn.