BRUSSELS — Belgium was reeling Monday after the country's likely new prime minister was asked on Belgium's National Day to sing the national anthem and inadvertently launched into the French anthem instead.

Asked Saturday by a reporter from a state television channel, RTBF, to sing the Belgian national anthem, "La Brabançonne," on the day commemorating the accession of King Leopold I of Belgium to the throne in 1831, Yves Leterme, a Flemish politician who is struggling to form a coalition government, smiled at the camera and blurted out, "Allons enfants de la patrie" - the first words of "La Marseillaise."

Pressed by the reporter as to whether he really thought those were the words, Leterme, the head of the Flemish Christian Democrat party, replied: "Oh, I don't know." Shortly afterward, he was filmed making a telephone call on his cellphone during a religious service, and, in a final gaffe, he proclaimed in an interview at the independence festivities that his countrymen were, in fact, celebrating "the proclamation of the Constitution."

The missteps by Leterme, who has annoyed Francophones by saying they are too stupid or unwilling to learn Flemish, came as Belgium, divided between Dutch-speaking Flanders in the north and French-speaking Wallonia in the south, is struggling to overcome its linguistic divisions in the face of a growing Flemish nationalist movement that supports an independent Flanders.