Montebourg is an ally of Segolene Royal, the French Socialist presidential candidate, and the spat follows the much-publicised tax-flight of Gallic rocker Johnny Hallyday to Switzerland amid a heated debate over taxation that has become a central issue in the presidential election campaign in France.
 
Calmy-Rey, a Social-Democrat whose one-year term began on January 1, noted that more than 100,000 French citizens cross the border into Switzerland every day to work, and that her country collected about 300 million Swiss francs ($240 million) in taxes last year for the European Union even though it is not a member of the bloc.
 
Each Swiss canton sets its own personal and corporate tax rates, which can be as little as half that of large EU members such as Germany, France or Britain.