The leaders of Germany and France have put on a show of unity on the 50th anniversary of the Élysée Treaty that sealed their post-war reconciliation.

Angela Merkel and Francois Hollande promised to put forward common proposals to deepen Europe's economic and monetary union by May.

The pair have had an uneasy relationship since the French President swept into office eight months ago, vowing to reverse German-backed austerity policies aimed at shoring up the euro.

But the leaders rejected the suggestion that ties between the two countries are difficult, highlighting the steps they have taken together to shore up the single currency bloc.

"It may be our best-kept secret that the chemistry actually works," Ms Merkel said.

The German leader refused to meet Mr Hollande during last year's French election campaign, while openly supporting his conservative opponent Nicolas Sarkozy.

Mr Hollande pointed to the fiscal compact on budget discipline, a December deal on banking supervision and the agreement to keep Greece in the eurozone as fruits of the strong relationship between him and Ms Merkel.

"It has not escaped you that we do not belong to the same political family. Despite that, if you look back at the past eight months, I'm very happy with what France and Germany have been able to accomplish to get the eurozone out of its crisis," he said.

"If you look at the results, it's clear we're on the same wavelength."

On one of the most divisive issues between the two countries - deeper economic and fiscal integration - the two promised to come up with joint proposals before a summit of EU leaders scheduled for June.

France and Germany have a different vision of a closer union, with Ms Merkel favouring tighter central controls over budgets and Mr Hollande seeking more solidarity and risk-sharing, in the form of a big eurozone budget to deal with economic shocks.

"It is about a deeper cooperation in economic policy with the goal of social security, employment, growth and financial stability," Ms Merkel told reporters gathered in the chancellery in Berlin for a joint news conference.

Festivities were held in Berlin 50 years after Konrad Adenauer and Charles de Gaulle signed the Élysée Treaty that sealed the post-war friendship between the former foes.