The leaders of France and Germany meet on Tuesday to deepen a 1963 treaty of post-war reconciliation in a bid to show that the European Union's main axis remains strong and counter growing eurosceptic nationalism among some other members.

"We want to give an impulse to European unity," Merkel said in her weekly podcast on Saturday.

As she waited to welcome Macron at the Aachen city hall to sign the updated treaty, some people gathered outside with blue and yellow EU balloons. Another group wore the yellow vests adorned by members of a grassroots rebellion against Macron.

Germany has for years sought greater influence within the international body, to which its closest allies the United States, Britain and France belong.

While making clear that Germany and France remain committed to the EU and NATO defence alliance, the agreement also signals that Berlin and Paris will combat efforts by some nationalist politicians in Europe to erode the 28-nation EU.

Facing new challenges from U.S. President Donald Trump in the United States as well as EU governments in Italy, Poland and Hungary, Merkel and Macron are keen to head off any breakthrough for eurosceptic parties in the European Parliament vote.

Franco-German treaties are supposed to be milestones in the process of European integration, paving the way for the bloc as a whole to deepen cooperation.

But its signatories, both of whom have struggled to maintain their authority over their own domestic politics, have failed this time to produce the wide-ranging vision to really enthuse Europhiles.

Eurosceptics also voiced their opposition. Alexander Gauland, leader in parliament of the Alternative for Germany (AfD), said: "French President Macron cannot maintain order in his own country. The nationwide protests in France are never ending. So it is inappropriate, if this failing president imposes visions on us for the future of Germany."

"The EU is now deeply divided. A German-French special relationship will alienate us even further from the other Europeans," he said.

"Relaunching" Europe will also have to wait until after Brexit is settled and this year's hard-fought European Parliament elections in May.

The original Elysee Treaty was signed in 1963 by Chancellor Konrad Adenauer and President Charles de Gaulle, who in the same year vetoed the British application to join the European Community, the precursor of today's European Union.