Belgrade  - Ultra-nationalists and the late Slobodan Milosevic's Socialists signed a deal Wednesday with outgoing Serbian Prime Minister Vojislav Kostunica's party to run the Belgrade city hall.

The coalition of Kostunica's Democratic Party of Serbia (DSS), the ultra-nationalist Serbian Radical Party (SRS) and the Socialist Party (SPS) also took the three sides closer to an alliance at national level.

Serbia held local elections together with a snap parliamentary poll on May 11.

Kostunica and SRS leader Tomislav Nikolic pledged to stop Serbia's progress toward European Union membership in protest at Western support of Kosovo's secession from Serbia.

Kostunica said the upcoming parliament would annul the pre- membership agreement pushed through days ahead of the May 11 poll by his pro-European rival, President Boris Tadic.

Tadic's Democratic Party (DS) won the most seats in the Serbian assembly - 102 out of 250 - but may be left out in the cold if the radicals, Kostunica and SPS forge a coalition of 128 seats.

Despite the alliance to administer Belgrade, the Socialists have so far not negotiated with the DS over a deal at national level, its officials said. (dpa)