Serbia's ruling liberals were narrowly ahead in elections for parliament and president last night, but will need to find allies to retain power, according to unofficial preliminary results.

Incumbent Boris Tadic and opposition populist Tomislav Nikolic will enter a run-off for the presidency on May 20 after taking 26.8% and 25.6% respectively, a result projection showed.

Television news reported Mr Tadic's Democratic Party got 24.7% in the parliamentary election, ahead of Mr Nikolic's right-wing Serbian Progressives on 23.5%. The result suggested the Democratic Party was well-placed to reform its coalition with a number of smaller parties including the Socialists of late strongman Slobodan Milosevic, who appeared to have polled strongly.

The constitution makes the prime minister more powerful than the president.

Mr Nikolic was once demonised by the West as Mr Milosevic's spiritual heir but says he shares the goal of taking Serbia into the EU.

Under the Democratic Party, Serbia closed a dark chapter with the arrest and extradition of Bosnian Serb genocide suspects Radovan Karadzic and Ratko Mladic, and in March became a candidate for EU membership.