(Adds comments by source)
By Andrés González, Alexander Hübner and Geert De Clercq
MADRID/FRANKFURT/PARIS, Aug 31 (Reuters) - French nuclear power engineering group Areva has rejected a non-binding offer from General Electric for assets belonging to the Adwen offshore wind power joint venture between Gamesa and Areva, sources close to the talks have told Reuters.
Several sources said General Electric (GE) is interested in some of Adwen's technology and its French offshore contracts, but not in Adwen's German operations and not in all of Adwen's commitments to build factories and create jobs in France.
"General Electric has made an offer for (Adwen's) assets, which is impossible to accept," one source said.
Another source said GE had made an informal approach but had not submitted a formal offer. GE has until Sept 17 to sweeten its bid and make a binding offer.
Officials at Areva, Adwen and GE all declined to comment.
Spain's Gamesa is being merged with German industrial group Siemen's wind power division to create the world's biggest builder of wind farms in a 10 billion-euro ($11 billion) deal, but Adwen has been a sticking point.
Adwen has contracts to build 1,500 megawatts of offshore wind power generating capacity on the French coast for utilities Engie and Iberdrola. These were awarded at above-market prices, but come with obligations to build factories and create jobs in France.
When Siemens and Gamesa agreed their merger in June, they specified that Areva had three months to decide whether it wanted to buy out Gamesa's 50 percent Adwen stake, or sell it to them.
This opened the door for an offer from GE, which wants to become a major player in offshore wind and has expressed an interest in buying Adwen.
GE also has contracts to build 1,500 megawatts of offshore wind power capacity on the French coast for EDF - a deal which it acquired as part of its takeover of French engineering group Alstom's power business in 2015.
These contracts too come with obligations for factories and jobs, and while an Adwen takeover would make GE the dominant player in the French offshore wind power market, that market is seen as too small to support the number of factories the government had envisaged.
A spokeswoman for Gamesa said the Adwen sale process was on track and there was no final decision made about it.
Siemens declined to comment. One source said that Siemens has no say in what Areva decides for Adwen.
If Areva does not find a buyer before the mid-September deadline, the most likely outcome would be for Areva to exercise its option to sell its share in Adwen to Gamesa, sources said. Gamesa values its 50 percent stake in Adwen at 60.6 million euros. ($1 = 0.8974 euros) (Additional reporting by Georgina Prodhan in London and Bate Felix in Paris; editing by David Clarke, Greg Mahlich)