The project was due to have been completed last month, to take its place as the world’s biggest offshore wind farm until RWE’s Gwynt y Môr project off Wales is ready in 2014. But it is unlikely to be completed now until the summer of 2012, at the earliest.

Weather delays, low subsea cable and turbine installation rates, and the bankruptcy of contractor Subocean have all contributed to delaying the project.

Fluor faces spiralling costs, as it has to bring in a new cable installer and “substantial” extra costs for additional maritime assets.