London - The world's largest offshore wind farm, with a projected energy generation of 1 gigawatt, will be built off the coast of south-east Britain, a consortium led by German power giant E.ON announced Tuesday.

Prime Minister Gordon Brown said the "flagship project" would play a key role in Britain's drive to cut CO2 emissions by 80 per cent by 2050.

Construction of the first phase of the London Array project, involving 175 turbines, would start later this year and could be generating power in time for the 2012 London Olympics, E.ON said.

E.ON and its partners Dong Energy of Denmark and Masdar of Abu Dhabi will invest 2.2 billion euros (3 billion dollars) into building the first 630-megawatt phase of the wind farm in the Thames Estuary near Southend.

The project will be sited over an area of 230 square kilometres, some 20 kilometres off the coast of Kent and Essex. It is estimated to displace the emission of 1.9 million tonnes of CO2 every year.

Once complete, the scheme will be the world's largest, and the first 1 gigawatt offshore wind farm in the world.