French President Jacques Chirac briefly walked out of this evening's European Union summit when the French head of the EU's industry lobby addressed leaders of the bloc in English.
A French official said Mr Chirac, Foreign Minister Philippe Douste-Blazy and Finance Minister Thierry Breton left the room when Ernest-Antoine Seilliere, head of the UNICE business lobby, began speaking in "the language of business" at a summit session with employers and unions.
He missed the former head of the French employers' body urging the leaders to "resist national protectionism in order to avoid a negative domino effect" in the EU's internal market - a veiled criticism of France and others who have sought to block cross-border takeovers.
Mr Chirac returned after Mr Seilliere had finished to hear another Frenchman, European Central Bank President Jean-Claude Trichet, addressing the leaders in French.
Trichet, a former Bank of France governor, almost always speaks English at the Frankfurt-based ECB.
English, French and German are the working languages of the EU which has no single official language. All 20 languages of the member states are used at summits, ministerial meetings and in the European Parliament.
French once dominated the EU, but English has overtaken it since the bloc expanded to take in Nordic countries in the 1990s and east European members in 2004.
Paris has fought a rearguard battle to preserve French as a main working language in Brussels, sparing no expense to offer free or heavily subsidised language courses to officials and diplomats from the new member states as well as journalists.