The European Union has postponed Thursday's signing of an aid-and-trade pact with Serbia, because of political infighting in Belgrade over the country's breakaway Kosovo province.

EU Enlargement Commissioner Olli Rehn says Serbian Prime Minister Vojislav Kostunica has blocked the deal, to protest a separate EU decision to prepare a police and administrative mission for Kosovo.

In Brussels Wednesday, Rehn said the aid-trade deal remains open and expressed regret over what he called "obstruction by certain politicians in Belgrade." For his part, Serbian President Boris Tadic urged Mr. Kostunica to stop interfering with state institutions.

The prime minister Tuesday called the aid-trade pact a European trap aimed at forcing his country to accept Kosovo's expected declaration of independence.

The postponed pact would promote political dialogue, ease visa restrictions and seek to expand EU trade and educational cooperation with Belgrade.

Tuesday, the chairman of Europe's leading security organization met in Belgrade with Mr. Tadic. The Serbian president, who supports closer ties with Europe, was re-elected to a second term Sunday.

Finnish Foreign Minister Ilkka Kanerva, whose country chairs the Organization for Security and Cooperation in Europe, congratulated Mr. Tadic on his victory. He also voiced continued support for political reforms in Serbia.

Kanerva visited the Kosovo capital, Pristina, today where he reaffirmed support for the OSCE mission in the province. He said the mission should continue regardless of political developments.

Some information for this report was provided by AFP, AP.