It comes as GE — which has ruled itself out of the offshore market — is in talks to acquire Alstom's power division.
"The ongoing construction of factories, the resulting job creation and the implementation of the [research and development] centre for offshore wind must be confirmed without delay," said Christophe Clergeau, vice president of the Pays-de-la-Loire region.
Alstom is building two factories at St-Nazaire to manufactue nacelles and generators for its Haliade-150 6MW turbine, which are due to start operating at the end of this year.
Two further factories for blades and towers should be commissioned in Cherbourg in early 2016. Alstom is also working on building up a local supply chain, and recently announced it will establish an R&D centre at Nantes. The company is also active in tidal energy.
"After several years of effort and collective mobilisation, after tens of millions of euros of investment supported by the local authorities, the marine renewable energy industry is taking off in the Pays de la Loire," Clergeau notes.
"Whether American or European, the takeover must be organised around a strong industrial ambition and must reinforce the key skills of France and the Pays de la Loire region," he adds.