Flemish separatists scored an unprecedented victory in Belgium's general election on Sunday and demanded a re-drawn federal state in negotiations to form a government.

New Flemish Alliance leader Bart de Wever, 39, ultimately wants independence, and his party triggered a political earthquake by winning the largest share of the vote -- 29.1 percent based on almost three quarters of official returns in Dutch-speaking Flanders.

Media projections showed they would pick up between 28 and 30 seats in the 150-member lower house, becoming the kingdom's biggest individual party.

"The N-VA has won the election today," NDe Wever, 39, told cheering, flag-waving supporters who burst into a rendition of the Flemish national anthem.

De Wever has said he is open to the idea of a first French-speaking premier since 1974 if that would bring more powers to Flanders.

"You don't have to like each other to work together," he said.

The Christian Democrats and the liberals, former partners in the government, suffered heavy losses.

Stressing that Flemish nationalists had to extend a hand to francophones to find a structure that functions, de Wever underlined that "we need to change the state together."

He has allies in his quest for fiscal or full independence, with the far-right Vlaams Belang scoring 12.5 percent, and the separatist De Decker list expecting to pick up about 3.7 percent.

"The challenge is enormous (but) the Flemish people have chosen change and we won't let them down," de Wever said.

He underlined that he will stand aside during talks seeking to nominate a new Belgian prime minister to replace current caretaker Yves Leterme, whose Christian Democrats trailed on just 18.4 percent.

"The job of prime minister for me is not important, the key is to get a deal. If it helps the francophones to trust us, I'm happy to make that sacrifice," he said.

But together with the Flemish socialists, the PS could form the largest group in parliament, meaning PS leader Elio Di Rupo could become the next prime minister.

It is the first time a party advocating the end of Belgium has won the most votes in a federal election.

But the N-VA will not be able to start devolving powers to the regions immediately in the country of 10.6 million people, which hosts the headquarters of the European Union and the Nato military alliance.

"Belgium is not about to split up, but it is set for a reorganisation," said Professor Marc Swyngedouw of the Catholic University of Leuven.

The electoral system -- effectively two elections with separate parties seeking votes from French-speakers and the majority Dutch-speakers -- means at least four parties will be needed to form a governing coalition.

The N-VA's lead in polls triggered a nationwide debate about the possible break-up of the 180-year-old nation, with richer Flanders splitting from Wallonia, where unemployment is about double the national average.

Parties from poorer French-speaking regions see devolution as a step towards Belgium's break-up, which they oppose, but all have said they would consider some reform of the state.

Belgium also takes on the six-month presidency of the European Union on July 1.


Agencies