The European Union's Lisbon treaty, aimed at streamlining institutions and raising the bloc's global standing, came into force on Tuesday.
In line with the treaty, the EU's first president, Herman Van Rompuy, has taken office, along with foreign affairs supremo Catherine Ashton.
Swedish Prime Minister Fredrik Reinfeldt, whose country holds the EU's rotating presidency until the end of this year, said that with the coming into force of the pact, "EU citizens are heading into a new era."
After the end of the year, the functions of the rotating presidency will be taken over by the permanent president.
Van Rompuy, currently visiting Slovenia, pledged to serve the 27-nation bloc "with determination and enthusiasm, to ensure that the European Council delivers added value and leadership for Europe."
The new president, who served as Belgium's prime minister until last week, was elected by EU leaders at a meeting on November 19.
MOSCOW, December 1 (RIA Novosti)