Brussels (AFP) - The far-right Flemish nationalist Vlaams Belang made strong gains Sunday in national, regional and European elections, partial results showed.
Voting in the triple election was also marked by a protest outside Brussels Gare du Nord station at which police said 200 "yellow vest" anti-establishment protesters were arrested.
The vote will set the stage for negotiations to form a government, five month after the ruling coalition collapsed and left Prime Minister Charles Michel in charge of caretaker administration with no majority.
But, with 15 percent of the votes counted in all three elections in the Dutch-speaking Flanders region, the Vlaams Belang was on course for 18 percent, around three times their score in the last elections in 2014.
The Vlaams Belang's advance came partly at the expense of the conservative nationalist N-VA, but Flanders will remain led by the right while French-speaking socialists have the lead in Brussels and Wallonia.
This will complicate any effort to agree a coalition in the 150-member federal all Belgium parliament that represents parties from both communities, underlining the rift in Belgium politics.
With 11 million people, Belgium is one of the EU's most divided member states. Dutch and French speakers choose separate candidates and parties. There is also a small German-speaking constituency.
This makes coalition building extremely complicated. Belgium took a record 541 days to form a government in 2010 and 2011 amid deep divisions between the Dutch speakers in Flanders and francophones in Wallonia and Brussels.
Making matters worse, economically booming Flanders votes traditionally to the right, while the socialists are the major political force in Brussels and post-industrial Wallonia, where unemployment runs high.
The N-VA broke party tradition in 2014 and joined the coalition government with Michel, a French-speaking liberal, as prime minister.
The coalition collapsed in late 2018 when the N-VA jumped ship in opposition to Belgium's ratification of a United Nations migration pact.
If the N-VA, which is headed by powerful Antwerp mayor Bart De Wever, fails to win a commanding score, analysts predict a long wait to find a stable ruling coalition.
Further results are expected later Sunday.