MADRID/FRANKFURT Spain's Gamesa (GAM.MC) said it has not reached any deal with Germany's Siemens (SIEGn.DE) on a planned merger of their wind energy businesses and negotiations remained open. The Wall Street Journal reported on Wednesday that Siemens and Gamesa were close to announcing a deal after pending questions had been resolved "in principle.""As of today, no decision has been made and no agreement has been reached," Gamesa said in a statement to Spain's stock market regulator. Gamesa and Siemens said in January they were discussing a possible deal that would create the world's biggest wind power business and bolster the German engineer's weak position in the onshore market. But the talks have stalled because of concerns linked to an existing joint venture between the Spanish company and France's state-owned energy company Areva (AREVA.PA). A source familiar with the talks said a draft agreement had now been found on Adwen but details were still being discussed. Two other sources said talks were ongoing to resolve "several" questions which were still open. Shares in Gamesa were up 4.04 percent at 17.14 euros at 1050 GMT (0650 EDT), one of the top gainer in Spain's blue-chip index Ibex .IBEX.(Reporting by Jose Elias Rodriguez, Andres Gonzalez and Julien Toyer in Madrid and Alexander Hubner in Frankfurt; Editing by Alexander Smith)