PARIS (Reuters) - French police have searched the office of EDF Chief Executive Henri Proglio as part of a German investigation into the 2010 purchase of EDF's stake in utility EnBW by the state of Baden-Wuerttemberg, a source close to the matter said.

German prosecutors opened preliminary proceedings in July into alleged links between Morgan Stanley's top dealmaker in Germany and one of Baden-Wuerttemberg's top politicians relating to the state's purchase of shares in EnBW.

The source added that Proglio's office was not the only one targeted and that people under investigation would be questioned after the searches.

A spokesman for the prosecutors office in Stuttgart, the state capital of Baden-Wuerttemberg, said that as part of the probe German police have asked their French counterparts to gather evidence in EDF and Morgan Stanley's offices in Paris.

He said, however, that EDF and Morgan Stanley staff were not under investigation in this case.

EDF declined to comment. Paris police also declined to comment, saying that this probe was led by German authorities and that French judicial authorities were not involved in the case. No-one from Morgan Stanley in Paris was immediately available for comment.

The southern German state of Baden-Wuerttemberg agreed to buy EDF's 45 percent stake in EnBW (Energie Baden-Wuerttemberg) for 4.7 billion euros ($6.14 billion) in late 2010, enabling the French company to cut debt.

Stuttgart prosecutors said last year that the ex-premier of Baden-Wuerttemberg, Stefan Mappus, was suspected of breach of trust and of having overpaid for the EnBW stake, while Morgan Stanley banker Dirk Notheis could have aided Mappus.

Mappus said at the time that he did not overpay and that the charges were unfounded. Notheis said that all of the accusations were without merit.

(Reporting by Alexandre Boksenbaum-Granier and Hendrik Sackmann; Editing by Erica Billingham and Sophie Walker)