German Chancellor Gerhard Schroeder yesterday threw his weight behind French President Jacques Chirac's faltering campaign to persuade French voters to back the European Union Constitution.

The close allies said after a meeting of the French and German governments that a French rejection of the treaty in a referendum on May 29 would be a severe blow to European integration and leave France trailing its European partners.

"France will find itself on the platform as the train goes past," Mr Chirac told a news conference with Mr Schroeder standing beside him and with the German, French and EU flags behind them.

"This treaty will allow France to be stronger in Europe, and Europe to be stronger in the world... A 'No' vote means taking responsibility for interrupting 50 years of European construction, 50 years of movement towards peace, democracy."

The Constitution is intended to make decision-making easier following the Union's enlargement to 25 members last May. All 25 member states must approve the charter for it to take effect.

The lower house of the German Parliament is expected to ratify the Constitution on May 12 without a referendum. But all opinion polls point to France rejecting the charter, despite the repeated urgings of its closest European allies, and there is a possibility Dutch voters will also oppose it in a similar vote on June 1.