The world's largest offshore wind farm produced its first electricity on Monday around 20 kilometres off the east coast of Britain, boosting the country's position as the world's top offshore wind market.

The first 151 wind turbines of the London Array project generated electricity for the first time and the remaining 24 will power up by the end of the year, owners DONG Energy (50 percent), E.ON (30 percent) and Masdar (20 percent) said.

Britain aims to build around 30 gigawatts (GW) of wind capacity at sea by 2020 to make use of high wind speeds for electricity generation to help meet the governments legally binding emissions reduction targets.

Once the London Array project is fully operational at the end of the year, Britain will have nearly 3 GW of offshore wind capacity in operation.

The London Array wind farm could be expanded to 870 MW if a second phase receives required permits, the owners said.