Another development at the summit in Brussels was the decision to make Serbia a candidate for EU membership.
The move sets in motion what could turn out to be a long process to bring the former Yugoslav republic into the bloc.
The decision is seen as recognition for years of political reform in Serbia since the war in the Balkans in the early 1990's, and subsequent improvements in relations with neighbouring Kosovo.
But not everyone in Serbia is in favour of joining the EU. On Wednesday, dozens of ultranationalists marched through the capital Belgrade to the offices of the country's pro-Western president Boris Tadic.
The Serbian Radical Party claims to have obtained over 200,000 signatures of people opposed to EU membership.