A French rejection of the European Union's constitutional treaty would result in the “fall of Europe,” Romano Prodi, former president of the European Commission, warned on Sunday.

His words came as the Yes campaign stepped up its increasingly desperate search for a strategy to turn the tide of public opinion ahead of the May 29 vote. In the starkest warning yet of the consequences for the EU if French voters reject the treaty Mr Prodi who was in office when it was drawn up told a French newspaper: “There would be no more Europe. We will pass through a long period of crisis.