Local elections in Belgium have resulted in widespread gains for the Flemish Nationalist Party (NVA), which wants to divide the country further.
The party is now the biggest political force in Flanders, the Flemish-speaking region of Belgium.
Its leader, Bart De Wever, also won the race to become mayor of Antwerp, Europe's second-biggest port city.
The NVA's victory comes amid a growing separatist trend in Europe.
There have been growing calls for independence from nationalists in Catalonia in Spain and Scotland in the United Kingdom, as the eurozone crisis tests loyalties across the European Union.
After their success became apparent, Mr De Wever immediately demanded negotiations "to enable both Flanders and Wallonia to look after their own affairs".
He has played down talk of secession from Belgium. He has said he wants to turn Belgium into a "confederation," in which the Dutch-speaking north has fiscal independence while continuing to share some areas, like defence, with the French-speaking south.
The NVA believes that wealthy Flanders should not be subsidising poorer Wallonia, which it accuses of wasting money.
Mr De Wever argues that the party is standing up for Belgium's Flemings, who make up 6 million people in a country of 11 million.
It is a position which helped them to win 27 out of 150 seats in the last general election in 2010, but also led to political paralysis when Mr De Wever could not come to an agreement with coalition partners.
The BBC's Maddy Savage in Brussels says he will now be looking to build on the party's success in local elections to take on Belgium's socialist Prime Minister Elio di Rupo in national elections in 2014.