Belgium is in crisis, apparently, though I have to say it doesn't really look it. At least, no more than it usually does. The theoretically handsome Place Flagey in Brussels, which was a building site three years ago, is still a building site, only more so and much muddier. The trains are running normally, but Bruxelles Midi station is as beaten-up and pissed-upon as ever. The frites remain excellent, of course, as does the chocolate. And in the street the people curse the taxman, as they have always done, and the price of petrol, which is new.

The papers and the politicians, though, are predicting apocalypse. Believe them, and the country is in the worst trouble of its admittedly brief history, or at the very least since the dark days of the last war. Because Belgium, remarkably, has spent the past 156 days without a government. And while this is plainly not yet in itself a catastrophe, there is a very real fear that the fragile and complicated arrangement of string and sticky tape that holds this impossible country together may finally be beginning to come unstuck. Belgium, it is whispered (and none too quietly), could soon be no more.

Should we feel remotely concerned by this? If you dislike unfeasibly potent beer, naff statues of permanently peeing boys, mayonnaise with your chips, and Tintin, maybe you will not. If, on the other hand, you feel a vague sentimental attachment to the idea of a country whose very existence, in the absence of anything resembling a national language, a national culture or much more than a century-and-a half of national history, depends on the virtues of goodwill, understanding and compromise, then you should.

Belgium's citizens, in any event, look pretty much resigned to it: recent surveys show that in the north as many as 63% think the break-up of their 177-year-old country, a place their prime minister-in-waiting himself has called "an accident of history", is now more or less inevitable. "The place has had it," says René Vanderweiden, a fiftysomething telecoms engineer queueing in the penetrating Brussels drizzle for a No 93 tram. "Maybe not now, maybe not in 10 years' time. But within my lifetime, I'd guess. The Flemings [Belgium's Dutch-speaking majority] want out of it, and they're no longer afraid of saying so. There's a scorn, and an impatience, that wasn't there before."

Sheltering from the rain in a stylish cafe in the Galeries St Hubert, Joelle Rutten, who works in a bookshop, blames the politicians. "We obviously don't need them," she says. "Look at us - we're all going to work, paying our taxes, nothing has changed. They're utterly out of touch with ordinary people, anyway, arguing about things that mean nothing to most of us. It's a scandal! They have no idea what they're doing at all."

Sadly, though, the politicians - or some of them, at least - seem to have a very clear idea of what they are doing. In a neat and functional town hall office in the neat and functional Brussels suburb of Halle, Mark Demesmaeker, deputy mayor, remarks cheerfully that he "can no longer see the value-added of Belgium, actually. There are six million of us Flemings, we work hard, we make money, and we're perfectly capable of standing on our own two feet. Indeed, we would be one of the wealthier small countries of Europe. For us, Belgium is simply counterproductive. We'd be better off without it."

It takes a while to get one's head around just how complicated Belgium is: this really is not your model nation state. Vanderweiden is a Walloon, from near Liège in the region of Wallonia, which forms, roughly speaking, the southern half of the country. He speaks French. Rutten is Brussels born, and speaks primarily French but, she claims, "not bad" Dutch. And Demesmaeker is a Fleming, from the region of Flanders, the northern half of the country. He speaks Dutch.

The Flemings make up roughly 60% of the population; the Walloons 40%. The two communities lead essentially parallel lives; outside the royal family, the national football team, the foreign office, the justice system and the army, no national institution - not a single political party, a TV station, a charity or even a university - serves them both. Consequently, running Belgium currently requires one federal government, three regional ones (because bilingual Brussels also counts as a region), and another three on top of those, one for each language group (French, Dutch and, just to make matters interesting, a small German-speaking community). Thankfully, the Flanders regional government and the Dutch-language community government are one and the same, so the lucky Belgians are today ruled by a mere six different administrations.

Add to that the fact that Wallonia was historically far richer that Flanders, but, with the decline of its heavy industry, is now considerably poorer; that unemployment in Wallonia is more than double that of Flanders, and that twice as many Walloons as Flemings are employed by the state; that a sizeable chunk of Wallonia's income comes from the taxpayers of Flanders and is spent (to be polite) in a rather relaxed, Latin kind of way; and - the icing on the cake, this - that Wallonia traditionally votes left while Flanders traditionally votes (quite far) right, and perhaps the real surprise is that Belgium has managed to survive as long as it has. As one of the country's more famous sons, the painter René Magritte, might have said: "Ceci n'est pas une nation." Although typically, like his other famous compatriots Georges Simenon and Jacques Brel, most people tend to think Magritte was French.

Anyway. The country's present crisis was precipitated by elections in June. These saw the Flemish Christian Democrats and Liberals emerge as the big winners, with the Christian Democrat leader, Yves Leterme, anointed prime minister designate and charged with forming a government. Unfortunately, the Flemings had campaigned on a platform of far-reaching further autonomy for Flanders; Belgium's regions already control their own housing, education, culture and transport, but the Flemings wanted responsibility for taxation, social security, economic policy, justice and immigration as well. Not surprisingly, none of the Walloons - not even the French-speaking Christian Democrats, in theory Leterme's natural allies - is prepared to go along with this, recognising full well the disastrous consequences for already-impoverished Wallonia of splitting the country's social services and sky-high national debt.

The most emblematic of the Flemings' demands, however, concerns what has become rather cryptically known in Belgium as "the BHV question". The BHV question is on everyone's lips. "BHV is crucial," politicians will say to you, in deadly earnest. "There can be no agreement on a new government without agreement on BHV." Many ordinary Belgians, to be fair, feel there might possibly be a few more important questions to be answered, such as when exactly the politicians are going to stop arguing about BHV and get on with running the country, but all recognise that this is a stumbling block. Here, somehow, lies perhaps the toughest test yet of Belgium's collective capacity to continue as a country. And like everything in Belgium, it is absurdly complex.

BHV stands for Brussels-Halle-Vilvoorde, the country's biggest electoral constituency. At present, BHV is a sort of island within Flanders. It is made up of bilingual Brussels (B) and Halle and Vilvoorde (HV), which are Flemish. However, the fortunate French-speaking constituents of H and V are currently entitled to vote for French-language political parties in Brussels (there being only Dutch-language parties to vote for in the rest of Flanders).

The Flemings want H and V to be split off from B - thanks to rising property prices in Brussels, they feel H and V are getting a bit too French. This would effectively deprive some 150,000 French speakers of the right to vote for French-speaking politicians. It may sound technical, but in Belgium it is a very big deal indeed.

At any rate, on the damp and chilly streets of Halle, barely a quarter of an hour's train ride from the capital, feelings are certainly running high. Here, as deputy mayor Demesmaeker politely explains, the local council has a Flemish language manifesto stating that Halle is a Dutch-language town, and intends to remain so. "We merely ask everyone to respect that," he says. "We ask people to integrate. We ask the shopkeepers to advertise only in Dutch, we demand that the street signs are only in Dutch, we expect everyone who comes to the town hall to address us in Dutch, and we ourselves will communicate only in Dutch. And we have an official who checks up on it all. It's perfectly normal, I think."

Some may see here the seeds of something rather nastier than a quest for linguistic integrity. But in any case, continues Demesmaeker, who is also an MP in the Flemish parliament, the root of the problem is that Halle's 10% - "and growing fast" - of French speakers show "very little willingness to learn Dutch. They come here, they see Halle as some kind of extension of Brussels, they walk into the shops and they say, 'Bonjour.' Many make no attempt. Don't get me wrong: I have nothing against Walloons. I go often to the Ardennes forests, in the far south, and there they are charming, completely different. But here . . . Well, there's a certain arrogance, I think. French was for so long the dominant language and culture here, you see. And the Dutch-speaking inhabitants of Halle, well . . . there are tensions. They don't like too many people speaking French here. They don't like some of the classes in our schools being half-full of French children."

Many of Demesmaeker's constituents seem to agree with him. "This is Flanders here, and we deserve as much respect as anyone else for our language and for our culture," says the owner of a shoeshop on the pedestrianised main street, Basiliekstraat. She does not want her name in the paper, because "these things are sensitive, especially for a shopkeeper - a client is a client." But, she adds vehemently, "if we go to Wallonia, we expect to have to speak French. It's only right. And it's only right that when Belgian French-speakers come here, they should speak Dutch. It's common courtesy. But most either can't, or don't bother." Outside the Ici Paris boutique, oblivious to the irony, Marie, who also does not want her surname mentioned, acknowledges it would be "a bit sad" if Belgium were to collapse over such a question. But, she feels, "there are laws in Belgium that were created for a very good reason. This is not a bilingual region, and it shouldn't become one". In the cheese shop, I exercise some rusty Dutch, and the woman behind the counter thanks me profusely for trying. Most, she says, do not.

Reinforced by such passionate sentiments, and no doubt irritated by the lack of any progress on their constitutional demands, Belgium's Flemish politicians last week took the historic step of voting through the split-up of BHV in parliamentary committee. Outraged, the Walloon MPs stormed out of the chamber in protest. In living memory, this was the first time that Belgium's unspoken pact had been broken: the politicians of one language community had forced a vote, against the wishes of those of another. It may not signal the end of Belgium, but the consensus among politicians appears to be that it does not bode well for the country's future.

In an elegant antique-filled office overlooking a park in the centre of Brussels, Charles Piqué, the capital's affable, Socialist, French-speaking minister-president, concedes that the vote had "a very, very strong symbolic value. It is not decisive, I don't think, not yet. But it marks another step in the ongoing process of Flemish intimidation. We have learned in this country, over the years, to compromise more and more to avoid these kind of situations. But this shows their determination, that they are prepared to increase tensions between the communities to such an extent. And BHV is only the start - it's just the beginning of the Flemish demands. They will now put the whole lot on the table: the full transfer of responsibilities, the further defederalisation of this country. What happens next is critical."

It would be a sorry end for a country whose birth was, to a large extent, our doing. In 1831, when the Catholic Flemings and Walloons split off from the Netherlands, Britain was interested in keeping the Dutch in their place, maintaining a buffer between France and Germany, and ensuring that all the Channel ports did not fall into the hands of one or other of them. We backed the fledgling state, placed Queen Victoria's uncle on its throne as Leopold I, and pledged military support. Germany's violation of Belgium's neutrality was, indeed, why Britain entered the first world war. The place has not done too badly: it did not exactly cover itself in glory in its colonisation of the Congo, but it was an early industrial power, and, in the 1950s, it did very well to grab the headquarters of the European Union.

But is it really necessary? That, increasingly, is becoming the question, if not quite yet for ordinary Belgians, then certainly for their political leaders and the media. The "Czechoslovakia option" of a more or less amicable divorce, with Brussels becoming a kind of international city state, is being openly discussed. So too, extraordinarily, is the notion that Wallonia might become part of France, which a poll this weekend showed the French would be perfectly happy to countenance.

Joelle Rutten, the bookshop worker, steadfastly refuses to believe that Belgium is on the brink: "We've grown up in this country; it's a nice country, a friendly country. It would be stupid, completely idiotic, to split it all up just because a few thick-headed politicians are so out of touch with reality that they can't see sense."

But for Demesmaeker and his Flemish friends, there now has to be, at the very least, major constitutional reform: "We could just about live with a confederation - two independent states that voluntarily decide what they can profitably do together. That would be sensible, and it's a very different proposition from what we have now," he says. "It's not that we're not prepared to help Wallonia; nobody wants a weak neighbour. But it would have to be on our terms: there would have to be transparency, efficiency, less waste. What we are not prepared to do is carry on as things are. This is a very, very deep crisis."

Unfortunately, says Piqué, for the Walloons and for Brussels, "an arrangement like that would be very, very difficult. In a federal state, based on cooperation and solidarity, everything is possible. In a confederation, where there's no real central government to resolve disputes, everything becomes much more problematic. And if the Flemish get exactly what they want out of all this, and make no concessions, and the Walloons start to feel humiliated and realise they've been left with nothing, then there will inevitably be a radicalisation. Future historians could well look back and say: 'This moment, right now, was this country's turning point.'"

The demise of Belgium, Piqué says, would be "a victory for selfishness". Also, it would be short-sighted, costly and sad. Call me sentimental, but on balance I agree. Outside, obviously, it is still pouring. But the tram comes, on time, and nobody on it looks any unhappier than they might reasonably be expected to look in Brussels in November in the rain. They may not be missing their politicians, the Belgians. But it is beginning to look like they might, in the not too distant future, be missing their country.