European foreign ministers have decided to ratify a long-stalled agreement with Serbia, taking the country further down the road to EU membership.
The ministers, meeting in Luxembourg, acted after the chief prosecutor of the UN war crimes tribunal said Belgrade had co-operated with its inquiries.
The UK and the Netherlands lifted their long-standing opposition to a key "aid and trade" deal with Serbia.
But ministers warned that Serbia has a long way to go before joining the EU.
The Stabilisation and Association Agreement, which Belgrade signed in 2008, offers wide-ranging benefits and was intended to set the country on the path to EU membership.
The latest breakthrough came after the chief prosecutor of the UN war crimes tribunal, Serge Brammertz, gave a positive assessment of Belgrade's co-operation.
But he also asked the EU to keep up the pressure until General Ratko Mladic is arrested.
He is accused of masterminding the 1995 Srebrenica massacre, in which up to 8,000 Bosniaks (Bosnian Muslims) were killed in one week.
So ministers simply noted that Serbia had applied to join the EU last year, but did not say when they would give their reply.
"Serbia has turned in a European direction, and we want to encourage that," said British Foreign Secretary William Hague.
Dutch Foreign Minister Maxime Verhagen said full co-operation with the tribunal would be a condition for Serbia's every step towards EU membership, and that EU countries could exercise their veto at each stage.
He also warned that Croatia had failed to deliver the documents necessary for the trial of an indicted war criminal, and until it did it could not conclude membership talks.
Croatia, which started negotiating EU entry terms in 2005, was hoping to join next year, but that now looks out of reach.