French Foreign Minister Laurent Fabius said a British referendum on whether to leave the EU was "very risky", ahead of a visit by Prime Minister David Cameron to Paris.
EU foreign policy chief Federica Mogherini called on Israel and the Palestinians to resume peace negotiations, saying the situation on the ground was "not sustainable."
The EU urged Burundi's government to prosecute the killers of an opposition leader and prevent the violence in the central African country from worsening.
Behind the kitsch, glitz and smoke machines of the Eurovision Song Contest -- hosted by Vienna -- hide more serious international geopolitical tensions.
Georgian President Giorgi Margvelashvili has warned European Union leaders against letting Russian aggression in Ukraine undermine the bloc's project of building closer links with ex-Soviet nations.
Hungarian Prime Minister Viktor Orban angered EU lawmakers and officials by insisting that Budapest had the right to debate closing the door to migrants.
French President Francois Hollande said that quotas for migrants in Europe were "out of the question" but said he supported a better distribution of refugees between EU countries.