Nick Clegg today said that it was a "scandal" that Britain did not have the capacity to produce the giant turbines needed for the offshore wind farms being planned for the North and Irish seas.

On a visit to Newcastle, the Liberal Democrat leader said that disused shipyards should be upgraded to allow them to produce the new equipment.

Under a Lib Dem plan, all port authorities on the North Sea and Irish Sea would be able to bid for a share of a £400m pot to convert shipyards into wind turbine plants.

Clegg said: "We need to make sure we come out of this recession with a rebalanced and green economy.

"New offshore turbines, with blades the size of the London Eye, need to be built and launched from modern docks, so we need to upgrade our shipyards to take advantage of this massive opportunity.

"Just imagine the docks and shipyards along the coastline of Britain coming to life and leading the world in this new technology.

"Expanding offshore wind will create jobs but unless we act now, these jobs won't be British jobs. It's a scandal that 90% of the £1.75bn contract for a wind farm off the coast of Kent is going to foreign contractors, with the turbines being manufactured in Germany."

He went on: "Investing in infrastructure for a new green economy not only helps create jobs now but will allow Britain to take its place at the cutting edge of this growing industrial sector for the future.

"Britain clearly has the manufacturing and engineering expertise to lead the world in this green technology but government must play its part in supporting this."

The Lib Dems believe 6,400 new offshore wind turbines will be needed to meet targets on renewable energy.

Conversion of shipyards would involve upgrading to make them suitable for construction and testing of turbines. They would also need to be deep enough for the boats needed to transport the blades and towers to the sites of wind farms in the North and Irish seas.