Germany insisted on Monday that the French rejection of the European Union constitution did not leave the treaty dead in the water, but the Franco-German engine at Europe's heart looked set to be overhauled.

The old axis -- often referred to as the driving force of the European project -- faced an uncertain future despite Chancellor Gerhard Schroeder's insistence that the partnership would endure.

Schroeder conceded that the clear-cut French outcome was "a setback" but said it was not the end of the road for the constitution, which Germany has already ratified without a referendum.

"It is a setback for the process of ratifying the constitution, but not its end," the chancellor said.

"It is also not the end of the Franco-German partnership in and for Europe.

"This is an opinion shared by French President Jacques Chirac."

Schroeder's Social Democrats (SPD) accepted that the result weakened the old axis.

"France's 'no' makes European integration more difficult. France's weakened position in European politics means the German-Franco drive for integration will now lose some of its impetus," the party said in a statement.

Ulrike Guerot, an analyst at the Berlin-based German Marshall Fund Institute, said Germany must now take the lead in guiding France out of the political chaos the referendum had created.

"What I wouldn't like to see is Germany falling in behind France. It should be the other way round, with Germany extending a hand to a France which needs to modernise and accept a dose of reality about the Europe of the future," Guerot said.

While German leaders stopped short of accusing French voters of betraying their fellow founding members of the EU, French Foreign Minister Michel Barnier put the result into stark perspective.

"This is the first time in 50 years that the French and Germans have diverged in Europe on a fundamental issue. Without this constitution, Europe is broken down politically," Barnier said on French national television.

The Franco-German conception of the EU faced being superseded by a "much more liberal Europe, one big supermarket", he said.

His German counterpart Joschka Fischer said it was "not the end of the process of integration" but called for a careful analysis of why 55 percent of French voters rejected the constitution.

However, he added, "we will not get a better treaty than this one".

Regret at the French refusal came from across the German political spectrum.

The leader of the conservative opposition Christian Democratic Union, Angela Merkel, who will challenge Schroeder at elections expected in September, said the outcome showed that politicians must make Europe easier to understand.

"And we will only be successful if we really take people's concerns and worries seriously," Merkel said.

"If we overstretch the European Union and fail to abolish excessive bureaucracy, we will have trouble making it work."

Anne-Marie Le Gloannec, a Berlin-based analyst for the International Research Centre for Political Science (CERIS), told AFP that the referendum "will be a blow to Schroeder who had visited France on a number of occasions to campaign for a "yes" vote."

Like other EU leaders, Schroeder insisted that the remaining 15 EU countries who had yet to ratify the treaty should continue with the process.

The constitution is designed to facilitate the transition to a 25-country EU, but all member states must approve the text before it can take effect.

Germany last week became the ninth country to ratify the constitution when the upper house of parliament, overwhelmingly approved the treaty.

The lower house earlier passed it with a huge majority.