On grand ceremonial occasions, nothing has the power to stir the heart and unite the public quite like the national anthem. Unless you are the new Prime Minister of Belgium.

Yves Leterme has not yet been officially sworn in but has already lost the confidence of half his country after reciting the opening lines of the Marseillaise - the French anthem - when asked if he knew the words to his country’s national song.

Belgium’s francophone newspapers today likened the gaffe to Nicolas Sarkozy, the French President, breaking into “God Save the Queen” on Bastille Day.

To add insult to injury, Mr Leterme then failed to give the correct reason behind the choice of July 21 for Belgium’s National Day.

“The proclamation of the constitution,” he said confidently, only to be reminded it was in fact the day that Leopold I became the King of the Belgians in 1831.

In a country already divided between the poorer French-speaking south and Mr Leterme’s prosperous Dutch-speaking heartland in the north, the blunder has re-ignited fears that the new government cares little for Belgian unity.

Known as “Mr Flanders”, Mr Leterme won the general election last month on a pledge to devolve more power to the regions. A poll today showed that a quarter of Belgians believe this could lead to the break-up of their country.

“This was no Belgian joke. There is a fear that this was a subliminal message to the French-speakers,” said Le Soir newspaper. When he is in Brussels “you could say that Mr Flanders is on a visit to a foreign country”.

Mr Leterme could be forgiven for some confusion. The Belgian national anthem, the Brabanconne (song of Brabant) has three versions in the three national languages, French, Flemish and German, which all have different English translations. The Flemish version, for example, opens with a reference to “our holy fathers” while the French extols “our dear mother Belgium”.

But the symbolism of his gaffe has not been lost on French-speaking Wallonia. The anthem was written in 1830 by a French-Belgian revolutionary who was later killed in the independence struggle with the Dutch.

Mr Leterme was challenged after an earlier poll suggested that three out of four Belgians did not know the words to any of the three versions. When the premier-in-waiting began with the words “Allons enfants de la patrie, le jour de gloire est arrivé", he was asked if he was absolutely sure that was his own national anthem. “Oh I don’t know,” he replied.

In the Flemish north, where Mr Leterme was regional prime minister and remains hugely popular, the mistake was dismissed as a storm in a tea-cup.

Het Laatste Nieuws, a daily newspaper, said that “real government negotiations are about to begin and the Marseillaise incident will have no effect at all.” De Tijd, another Flemish daily, added: “Above all this reflects the fear of francophones about a reform of the state - and the financial consequences for them.”

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