PARIS (Reuters) - General Electric Chief Executive Jeffrey Immelt said in a letter to French President Francois Hollande that if GE were to buy the energy unit of Alstom, it would boost employment in France and locate global headquarters for several key businesses in the country. GE confirmed that the letter, published by French financial daily Les Echos, was authentic. GE said it would also locate the headquarters for grids, hydraulics, offshore wind and steam turbines in France, and would work with the French government, utility EDF and nuclear group Areva to protect France's nuclear sector and its exports. It would also consider selling Alstom's wind turbine activities to French investors. Separately, a source close to Alstom told Reuters the company will issue a statement about the possible sale of its energy unit on Wednesday morning. (Reporting by Geert De Clercq; Editing by Erica Billingham)