PARIS- The European Commission would be making a mistake if it blocks the merger between Siemens's SIEGn.DE rail business and France's Alstom, ALSO.PA France's government's spokesman said on Wednesday.

"A rejection by the European Commission would be an economic mistake but also a political failure. It would send the wrong signal to the people of Europe at a time Europe... has failed to protect European citizens... its companies," government Benjamin Griveaux told reporters.

Antitrust commissioner Margrethe Vestager in December voiced doubts over the impact that the Franco-German deal would have on other high-speed train sector. 

(Reporting by Michel Rose and Jean-Baptiste Vey; editing by Richard Lough) ((michel.rose@thomsonreuters.com; +33149495071; Reuters Messaging: Twitter: https://twitter.com/MichelReuters))