Simenon would have loved it

Andrew Marshall on the web of intrigue surrounding Nato's secretary- general Willy Claes

Who killed Andr Cools? The death of the Belgian politician, gunned down in 1991, is slowly being unravelled by magistrates in Lige. But as it is untangled, so a widening circle of the country's leading figures are being caught in a web of allegations of corruption. The latest to find himself wrapped up in the investigations was General Jacques Lefbvre, former chief of staff of the Belgian air force. He was found dead in a hotel room on Tuesday with suicide suspected.

This would not be of great interest to anyone outside Belgium but for one thing. Pre-eminent among those who have found themselves trapped in the threads of investigation is Willy Claes, a man who only five months ago was appointed secretary-general of Nato, the alliance's senior civilian official. Mr Claes is in an embarrassing position, and it is increasingly embarrassing to the other Nato countries as well.

At the centre of the affair is the purchase of 46 helicopters for the Belgian army in 1988 from Agusta, an Italian company. Agusta is alleged to have paid bribes to the two Belgian socialist parties to obtain the contract. It has always denied that any such payment was made. Mr Claes was economics minister when the contract went through. He initially denied knowing anything about an offer of payments to the party. "I have never, from anyone or anything or anywhere, heard or received any suggestion or proposal whatsoever to set up such a thing," he said on 22 February. It was an unequivocal statement.

But then Etienne Mange, formerly the party treasurer, who is under arrest, said he had indeed told Mr Claes of the offer, as well as two other key party figures, one of whom is the Belgian foreign minister, Frank Vandebbroucke. Ah, yes, said Mr Claes, that meeting: "That I vaguely remember."

Mr Claes, in other words, conceded that he had indeed discussed the issue. It does not seem plausible, however, that he had forgotten or could only vaguely remember a meeting that touched on a subject that has so dominated Belgian politics for five years.

Mr Claes said he had refused to countenance any such payment. Mr Mange went ahead anyway, apparently using the money to prop up the Socialist party and its organs, possibly including De Morgen, then the party newspaper. On the basis of Mr Claes's testimony, leading party figures were unaware that the party had received a sum of more than £1m. And it may not have been the only such payment: there have been allegations that cash changed hands over other contracts, including the refitting of Belgian fighters. Gen Lefbvre's name has also been linked to this.

The investigation into this affair began with a single event, still unexplained: the death of Mr Cools. In July 1991 Mr Cools, a tough Socialist party boss, was shot in a parking lot in Lige as he left his apartment with his long-time mistress. Some have speculated that he was preparing to blow the gaffe because some of the side-benefits of the Agusta deal had failed to materialise.

An investigation under the tough Ligeois magistrate Vronique Ancia quickly started digging up all kinds of dirt, and before very long heads were rolling, starting with three leading Francophone politicians last year.

It is an immensely complicated matter, perhaps appropriately for an investigation centred on Lige - the home town of Georges Simenon. Floating around this affair are countless other dirty little secrets. There is a dense mass of unexplained events in Belgium, which is a strange, subterranean country, far from the dull ordered greyness that the British usually imagine. It is a place of shifting, hidden meanings, intrigues, closed-door deals and secret understandings.

There are questions about stolen bonds, about the death in Brussels of Gerald Bull, designer of the supergun, about links to other Belgian arms contracts. Last week Philippe Moureaux, a former deputy prime minister and acolyte of Mr Cools, claimed that a new witness in the Cools case had revealed details of "a mafia organisation which touches the political world and other groups". There are a number of links between the Belgian scandals and those in Italy. The Agusta affair really burst into the open after the company was investigated in Italy as part of the "clean hands" probe. Some of the key bagmen were Italian. As in Italy, cash seems to have been swallowed up to keep the party machines rolling, a little sticking to the hands of those involved.

But it is too easy to pigeon-hole the scandal as either just a little local difficulty, or as the spread of contagion from Italy. There are many familiar elements here from other European countries: payments to prop up party funds, dodgy arms contracts, and a political class that is finding itself increasingly estranged from the electorate by revelations of corruption and concealment. There are elections in Belgium in May, and they are likely to see a further collapse in votes for established parties of government, just as in Italy, France, and Spain.

As with Agusta, many of the scandals that have afflicted Europe stem from the close links between the state and defence companies, from the involvement of state agencies in arms sales and from the corruption that is endemic in the defence market. If you think Britain is exempt from this, just wait until you read the forthcoming report of the Scott inquiry into the arms-to-Iraq affair.

There is more than an irony in Mr Claes's involvement in this investigation, as the head of an organisation committed to the security of Europe. There is really only one threat to the security of a country like Belgium, and it comes from within: from the corruption and contempt for democracy of some of its leading politicians and officials. Nobody is planning an all- out attack on Belgium from outside: instead, the institutions of the state are slowly collapsing from within.

There is a low-level conflict going on, in Belgium as in several European countries, between the forces of law who are trying to cut through the webs of deceit, and those - often in positions of power - who are doing their utmost to make sure that nothing gets found out, never, ever. The tensions of the Cold War helped to keep the lid on this. Its end, and the explosive political decompression that has followed, has shattered many of the convenient old lies that sustained sharp practices. They have simply helped to make evident what has always been true: the core is rotten.

Andr Cools was caught up in this war. No one knows, as yet, who pulled the trigger, or why; perhaps, some Belgians believe, no one will ever know. There are many conspiracy theories, and some of them may just be true. If Willy Claes knows any of the answers, it is better for him - and for Nato - that he comes out with it, quickly and in public.