Blok president Frank Vanhecke is expected to establish a new party
Belgium's highest court has ruled that the country's Flemish nationalist party, the Vlaams Blok, is racist.
The decision means that Europe's most successful far-right party will be forced to disband - and re-form under a new name.
The ruling - confirming an appeals court judgment that the party was guilty of racism and discrimination - means that the Vlaams Blok can no longer benefit from state financing, while anyone who continues to work for it will henceforth be committing an offence.
A quarter of voters in Flanders, the Dutch-speaking northern half of Belgium, support its policies - independence from Belgium and repatriation of immigrants, especially Muslims.
Its popularity has surged relentlessly - from 10.4% in 1991, to 12.3% in 1995, 15.4% in 1999, and 18% in 2003.
This year's 24.1% in the Flemish regional election included 250,000 extra voters compared to the previous year and made it the biggest single party.
It is kept out of power only by the so-called "cordon sanitaire", an agreement among all the mainstream parties to exclude it from any coalition government.
But many observers believe the cordon sanitaire itself brings the Blok votes.
Professor Stefaan Walgrave of Antwerp University says it is precisely the Vlaams Blok's pariah status, perennially kept out of government, that helps to increase its popularity.
"The difference here, compared to other countries, is that this party is seen as fighting against the establishment. By always being kept in the opposition it can claim to be the only party fighting for ordinary people against the political elite."
But the Vlaams Blok has also taken strides to soften its image and become "respectable".
Some years ago I watched Vlaams Blok skinheads urinating on a Belgian flag. Nowadays its suave, well-dressed and suntanned leaders prefer to spread the word not at raucous political rallies but at barbecues and cheese and wine evenings.
At one such event last month in Schoten, a suburb of Antwerp - where more than a third of voters support the Blok - 100 party activists sipped wine and assured me: "You won't find any skinheads here".
Defending Flemish identity
Indeed, the public was, not exactly genteel, but stolidly middle-class - good burghers of Flanders outraged both by the way they feel they subsidise the French-speaking south of Belgium, and by the influx of foreigners into the country.
Party leader Filip Dewinter in more confident times
The party's leader, Filip Dewinter, says the Vlaams Blok's goal is to defend the Flemish identity, both by securing independence from Belgium, and by keeping out immigrants.
He is unashamed about singling out Muslim immigrants, and denies that this kind of talk leaves him open to accusations of xenophobia or racism.
"Not at all. I think we should recognise that cultures are different and not all cultures are equal.
"When I see Muslim culture I think that our culture is superior. Our values, our way of life are superior and we have to say so. I don't think the way of life of Muslims is compatible with our way of life."
Floating around the cheese and wine tables was Marie-Rose Morel, who with her beauty-queen looks is the epitome of the new-look Vlaams Blok. At 32 she is the party's youngest MP.
"What attracted me to the party," she says, "is that they are very straight, they don't play political games, and say what they mean."
A softening approach?
Dewinter acknowledges that this amounts to populism, "if by populism you mean breaking taboos and saying what ordinary people think, even if it's politically incorrect".
The party last weekend softened its approach on immigration, and renounced its call for the repatriation of large groups of non-European immigrants "unless they reject our culture and certain European values".
Dewinter told a Flemish newspaper: "A woman who wears the veil in public is demonstrating that she is not integrated and must draw the consequences."
Dewinter and his colleagues were prepared for Tuesday's court ruling, already considering a new name for the party that will emerge from the Vlaams Blok's ashes.
"Perhaps the Flemish People's Party, or Flemish Freedom Front, or Vlaams Belang (Flemish Interest)," says Dewinter. Some even suggest renaming it simply "Vlaams Blok+".
Analysts here believe that the move will simply increase its status as the underdog of Belgian politics, and persuade even more Flemish people to vote for it.