A two thirds majority of Antwerp voters has voted for democratic parties

Prime Minister Guy Verhofstadt

He admitted he had been surprised by the gains, but said the result showed the majority of Antwerp's voters had not voted for the party.

Belgium's other political parties have also reiterated their pledge never to form a coalition with the Vlaams Blok, which advocates repatriation for immigrants.

Non-cooperation

Mr Verhoftstadt welcomed their stance, and said their policy of non-cooperation would eventually ensure Vlaams Blok's disappearance.

Filip Dewinter says his party should be allowed into government

Vlaams Blok's leader, Filip Dewinter, attacked their agreement - known as the cordon sanitaire - as undemocratic and accused his rivals of insulting the electorate.

Mr Dewinter is also threatening to disrupt business in Antwerp's city assembly if his party is not recognised.

"I think that the so-called democratic parties, if they are really democratic, have to step aside and offer the winning party,the chance to govern this city," said Mr Dewinter.

Some fear the increase in support for the Vlaams Blok could lead other parties to adopt similarly right-wing policies in an attempt to emulate its success.

Far-right policies

At last year's general election, the Vlaams Blok became the third largest party in the economically powerful region of Flanders, which it argues should become a separate Flemish state.

The elections have been keenly watched by the EU

Vlaams Blok's manifesto includes plans to close down mosques, and institute separate schools for the children of immigrants who have failed to integrate.

The party and its supporters also want an immediate end to all immigration to Belgium, which they say is clearly linked with crime.

The polls were seen as a key test of support for the party, which has seen a huge rise in popularity in local and general elections during the last 10 years.

Filip Dewinter says he has been inspired by the example of Austria, where the far-right Freedom Party was invited to join the government coalition.