Serbia's feuding reformist parties are preparing for talks on forming a coalition government in an effort to keep the ultra-nationalists, who won the most votes in Sunday's parliamentary elections, out of power. But, the talks will be difficult.

An exploratory meeting of Serbia's moderate parties produced little agreement on the new government.

The leader of the Democratic Party of Serbia, Vojislav Kostunica, has ruled out participation in a government with the party of late Prime Minister Zoran Djindjic, who was assassinated March 12.

Mr. Kostunica, who was briefly president of Yugoslavia, never forgave the late prime minister for extraditing ousted leader Slobodan Milosevic to the U.N. War Crimes tribunal in The Hague.

Serbia's outgoing prime minister, Zoran Zivkovic, told Serbian media he has offered his party's support to a minority government led by Mr. Kostunica's Democratic Party of Serbia, provided it continued his reform policies.

But at least one other crucial political group, known as the G-17 Plus Party, says it would not take part in a government without Mr. Djindjic's Democratic Party.

The big winner in Sunday's elections was the ultra-nationalist Serbian Radical Party, which obtained 82 of the 250 parliamentary seats. But this does not give the Radicals enough votes to form a government.

European institutions are worried the radicals wield enough political power to derail much needed reforms, and urge the pro-democracy parties to unite. European Union Foreign Policy Chief Javier Solana has appealed to Serbia's four main reformist parties - the Democratic Party of Serbia, the Democratic Party, the G-17 Plus Party, and the Serbian Renewal Movement-New Serbia - to stop feuding.

Analysts predict, without a united government of the pro-democracy parties, key economic reforms will likely stall and crucial policy initiatives, such as Serbia's first post-war dialogue with ethnic-Albanian leaders of Kosovo province, will be put on hold.