Brussels  - The European Union on Wednesday welcomed the transfer to the international war crimes tribunal in The Hague of former Bosnian Serb leader Radovan Karadzic.

The European Commission, the EU's executive, is "satisfied" that the transfer has taken place, a spokesman said.

It is "a significant step for international justice, first of all, it is a significant step for Serbia and also for EU-Serbia relations," he said.

Karadzic, who was arrested in Belgrade on July 21 after almost 13 years on the run, was transferred to the Dutch-based International Criminal Tribunal for the Former Yugoslavia (ICTY) in the early hours of Wednesday morning.

He is set to face charges of genocide and crimes against humanity committed during the Bosnian war from 1992 to 1995.

The EU has long said that all the states of the Western Balkans, including Serbia, should join the bloc when they are ready to do so.

However, on Tuesday representatives of EU member states confirmed that they would not offer Belgrade closer cooperation until Karadzic had been transferred and ICTY's chief prosecutor, Serge Brammertz, confirmed that Belgrade was fully cooperating with his organization.

Officials in Brussels say that Brammertz is due to visit Belgrade to discuss cooperation in August.

On Tuesday night Serb ultra-nationalists rioted in Belgrade in protest at Karadzic's extradition. Some 27 policemen and 21 civilians were injured, including two journalists. (dpa)