Adwen, owned 50:50 by Gamesa and Areva, offers 5MW and 8MW offshore turbines. Siemens is already the largest offshore wind turbine supplier in the world and is uninterested in taking on its rival, according to reports.
An option would be to seek a buyer for Gamesa's stake, but there are few manufacturers that appear suitable to do so.
Adwen also has a commitment to build two factories at in France to supply the 8MW nacelles and blades for offshore projects totalling nearly 1.5GW.
Siemens would not be prepared to build the factories on the basis of these contracts, none of which are yet confirmed, Reuters reported.
This could jeopardise the contract for the three projects, which was awarded partly on the criteria of local manufacturing.
While Siemens and Gamesa were unable to comment, Areva simply said it "remains particularly vigilant to protect the interests of our customers and that the engagements for the French offshore wind industry are maintained".
For its part, Adwen is continuing with plans to build the two factories and will submit building applications by the summer.