On the opening day of the two-day summit on Thursday, Jacques Chirac, the French president, walked out after a French business leader spoke in English, adding linguistic patriotism to the disputes over economic nationalism.
A leading goal of the summit is to define how EU countries can coordinate energy policy, by negotiating jointly with suppliers such as Russia or by helping any member country suffering from a sudden supply cut-off.
Jose Manuel Barroso, president of the European Commission, said: "I'm very delighted that the [leaders are] backing our call for an energy policy for Europe, that it makes sense to have a common strategy for Europe."
Wolfgang Schuessel, the Austrian chancellor, whose country holds the bloc's rotating presidency, said a lot of work remained but decisions made on Thursday would lead to a total change of EU energy policy within the next decade.
Disputes over cross-border mergers and liberalisation in the energy sector, however, overshadowed the official agenda.
Barroso said: "We cannot be open for business with the rest of the world and closed to each other.”