The commemoration took place on Sunday at Reims cathedral, where the then German Chancellor Konrad Adenauer and French President Charles de Gaulle attended a landmark reconciliation mass 50 years ago to the day.

That symbolic meeting led to a friendship document - the Elysee Treaty - between the two countries only months later. This forms the basis of mutual cooperation to this day.

Hollande and Merkel first braved the damp weather to meet members of the public gathered in streets close to the cathedral. They went on to unveil a reconciliation plaque written in German, mounted alongside one written in French at the original ceremony.

The reconciliation on July 8, 1962, marked a turning point in relations between the two countries, with memories of the Nazi occupation of France less than two decades earlier still painfully fresh.

After the service, Hollande and Merkel each gave a speech outside the cathedral.

Hollande said that Adenauer and de Gaulle had paved the way for achievements such as the single market, the reunification of Germany and the setting up of the single currency.

"Who would have though in 1962 that their successors would be capable of going so far, so swiftly together," he said.

Chancellor Merkel paid tribute to the men for helping to establish the architecture of a new relationship between France and Germany - and of Europe as a whole. "They opened a new chapter. These two great statesmen in this cathedral laid the basis for a new grandeur," said Merkel, before going on to urge all Europeans to show unity in light of the eurozone financial crisis.

Having grown up in East Germany, Merkel drew attention to the fact that, in her youth, she had viewed the improving relationship betweeen France and West Germany from behind the Iron Curtain.

"I am very please to no longer be a passive observer but to be someone who actively participates in building Franco-German relations."

Merkel concluded with a quote by de Gaulle; "Long live Franco-German friendship," she said.

Wartime graves vandalized

Sunday's commemoration was marred somewhat by the desecration of First World War gravestones of some 40 German soldiers just 40 kilometers (25 miles) east of Reims.

The vandalism at Saint-Etienne-a-Arnes was strongly condemned by French Interior Minister Manuel Valls.

According to reports, wooden posts marking the graves had been pulled out of the ground - with some being burnt on a campfire.

"An enquiry is underway and all means are being employed to find those responsible for this terrible desecration," his ministry said in a statement.

More than 12,000 German soldiers who died in World War I are buried at the cemetery.

rc/jm (AFP, dpa)