From Belgium comes the multi-talented Wim Mertens, a contemporary music composer with a nice line in repeating piano patterns, sampled acoustic sounds, and Renaissance singing. It's a curious mixture, but it works.

Belgium. Land of flat fields, good lager and... almost nothing of any musical interest at all. Try writing down the nation's contributions to this century's musical development, and chances are you won't need a second postage stamp. The most Britons ever see of Belgium's native music is the latest aberration perpetuated in the name of Eurovision harmony. And just imagine what would happen if we were judged on the likes of the Brotherhood of Man and Mary Hopkin...

But there is musical life in Belgium. More specifically, there is a brilliant young systems composer by the name of Wim Mertens — though it says a lot for established channels of communication that I first heard of him through his book on American minimalist composers Young, Riley, Reich and Glass.

Mertens' own music, it turns out, has an affinity with that of Glass and of Michael Nyman, but clearly he has a voice all his own, compellingly lyrical without being trite or sentimental, a pure, precise music that's often haunting and starkly beautiful. A comparison with the still perfection and 'removed longing' of Renaissance painting and sacred music is more apt than it sounds, but at the same time, Mertens couldn't have developed as he did without the music of the minimalists. Repetition is important for him, and his arpeggiated style is reminiscent of Glass'.

The composer visited these shores recently to give a solo concert (piano and vocal) at the ICA in London, and it's there that I am introduced to a soft-spoken, reserved man whose frail appearance gives no clue to the powerful performance he's to give a few hours later.

Fast-talking he is not (Flemish is his first language and it doesn't help), and I'm glad time is on our side. But his opinions come across as being carefully considered. More than perhaps any other quality, Mertens displays an ability to think at great length about music — both his own and other people's. Yet it seems the Belgian's contemplative days are all but over.

'From the ages of 20-28 I thought a great deal about music, and I was a musicologist and I wrote the book. But I am not going to write any more about anything in music. That verbal side does not really exist, it is not alive in me any more; I'm never going to stimulate that side of me again.'

Mertens is now 32 years old. He began composing what he terms his music quite recently. In fact, he's able to pinpoint the exact date: May 29, 1981.

'We're going to have a small celebration in Brussels: my fifth birthday!' he adds wryly. It was on that day that he created 'For Amusement Only', a mixed-media performance 'for two Bally pinball machines, pre-recorded tapes, microprocessor and video' — an oddball mixture, and one Mertens hasn't attempted to use since.

A little while later, he formed an ensemble — Soft Verdict — in the Reich/Glass tradition. Since its formation, the group has played his music in France, England, Italy, Belgium and Japan. But while many people mistake Soft Verdict for being a regular line-up, Mertens is at pains to stress that it's a free-floating aggregation of musicians, a flexible arrangement that's necessary because Mertens' instrumentation doesn't bear much resemblance to that of a 'band'.

Five years of composing have brought six records, with a seventh due out in three or four months' time. Mertens tailors the record format to the amount of music he wants to produce: thus he's made two albums, a double album, a 12-inch single, a 7-inch single and a mini-album. Individually, his pieces can last anything from two-and-a-half to 19 minutes.

Mertens was not a latecomer to music, though. His education began at the age of eight when he took up studying classical guitar, piano and theory at music college, and ended at the Brussels and Gent Conservatoires, where he studied piano and musicology. Yet although he composed music from the age of nine or ten, Mertens never studied composition — a fact he considers important to his own subsequent musical development.

What he did study was European music after World War II, which meant coming to grips with the heady delights (and frustrations) of Stockhausen, Boulez, Berio and the rest of them. This was the predominant 'new music' at the time, but it was not a music which inspired Mertens.

Instead, he turned to the music of the American minimalist composers, travelling to the States on several occasions and submerging himself in the artistic life there. He participated in the New Music America festival in Chicago in 1982, producing a cassette of interviews with and performances by such composers as John Cage, Meredith Monk, Glenn Branca, Robert Ashley and Harold Budd.

Back in Belgium, he began championing the cause of 'minimal' music, recording concerts for Belgian Radio and Television (where he works as a musical producer) by the likes of Philip Glass, Steve Reich, Terry Riley, Gavin Bryars and Urban Sax.

'The real influence the American composers had on me was that I was convinced I should start making my own music', he says.

'One reaction I had to America was that there was a lack of personal style and identity. I feel that if you have some sort of personal aspect, you can develop your skill much better. Nowadays too many people are working in such different ways, with each piece being a "new" piece, using new techniques and so forth. That's very much against my own feeling, which is to retain a clear style and identity.

'Now I'm seeing that I should be looking back to the roots of music in my own country. I'm convinced that I don't want to make a world music, or a third world music. I don't want to be influenced by Indian music, Balinese music or African drumming.'

More than this, Mertens sees no future in currently fashionable 'culture clash' music, and feels it's a mistake for the media to try to bring different musics together. 'Instead I want to look back into my own heritage — the material I'm discovering will provide its own techniques of composition. That's my approach.

'I think it's more relevant and realistic today that one person can only present their own situation. There's no aim for an absolute truth any longer. I'm just aiming for my own truth.

'There's the same problem in Belgian pop music. There's a very active scene, but no real identity. Pop musicians there make the same mistakes as composers who take compositional techniques from India or from Africa, because they adopt the techniques and the gimmicks of American and British pop music. So there's a lot of confusion. I really think you have to wait until you can connect with your own background. Although I've composed since the age of nine or ten, I was nearly 30 before I started writing my own music.'

Does Mertens think the present confusion has anything to do with instrumentation?

'The fact that people throughout the world are using DX7s creates a very new situation. The evolution of instruments and their techniques influences very much the kind of music people write. So if a certain commercial market presents these instruments all over the world, then obviously they will influence people in Africa or in Japan, say. But of course, it is also normal that instruments which have developed step by step in a particular location will be used there better than they will somewhere else. If you bring electric guitars to Africa, which has happened, then their use there is less interesting than in Britain or in America.'

The heritage Mertens refers to is that of 15th and 16th Century Flemish music, and it's an interest that stems from his earliest musical memories of hearing his father sing in church, where the sacred music of that time is still performed. Significantly, he's not so much interested in the structural aspects of the music as in its feel: 'a sort of clarity in the top voice, for instance, which really takes you away from the ground, as if you have a view of eternity.'

This influence is clear in his own music, providing one of its most distinctive and appropriately uplifting qualities. 'Vocal' lines are given either to the soprano sax, or to an early-music-trained voice.

Does all this history-book studying mean Mertens is looking for a national music?

'No. There is no such thing as a national situation any more. Music has much more to do with how you touch certain things, with very basic human values which go further than national situations and problems.' And even though American minimalism played a significant part in shaping Mertens' career, he has a few harsh words to say about that genre, too. His main criticism surrounds minimalism's 'anti-personal' mood, a symptom of the style's emphasis on process rather than personal expression.

'I always find that every single musical line, every motif, every melody is such a fragile thing, carries such important information. Melodies should be treated with care, not just be part of a process. You should treat them as being very closely related to yourself, try to refine them, to develop them; it's a life's work.

'But at least the minimalists stay honest to themselves, which is the important thing. And they are great masters, all of them.'

So systems music is OK as far as it goes. But how far afield does Mertens think the style's influence has been felt? Steve Reich's first tape piece 'It's Gonna Rain' has been called the first rap record, while more realistically, Kraftwerk's systems-influenced material has in turn influenced early electro dance music...

'I think that maybe developments in popular and classical music happened at the same time. It's not that pop musicians must have been influenced by developments in the classical world. I think maybe people like Jean-Michel Jarre and Klaus Schulze simply wanted to express a mechanical approach to music. It's more of a synchronous development in different areas — something's in the air, and it can be translated into different musics.'

Times have changed, undoubtedly. At one time it was trade routes and wars that defined the paths of artistic evolution. Nowadays, mass communication means artists in all fields are subject to a plethora of cultural and social influences, not least from their own work.

'What kind of feedback did Bach have?' muses Mertens. 'He would hear, say, a cantata of his just once, plus maybe a few rehearsals, and with that information he would go on to write a new piece. But the feedback for a composer today involves records, recording studios, critics, reviews... all of which determine what he will do in his next piece. Whether or not a piece is recorded, for instance, and if so the way in which it is released, will affect him, will affect his final product. That's how things work, and that's what determines whether a composer becomes relevant for his epoch.

'I accept living with these conditions: the only question is how to deal with them. You can do many different things, and you can and should react. I decide, for instance, what output I want to give, what I want to tell you: I won't tell you something that will harm me personally or musically.

'But this situation creates an enormous problem for many people — for pop musicians particularly. The way they're treated... In that sense I am quite happy that my music is not so easy to categorise or define. Maybe that's why I draw together different elements in my music, to give me some space: it's a kind of tactic.'

As already mentioned, Mertens is well aware of the effect a new instrument can have on the music a composer writes, and much of his own music is written for familiar acoustic sources: the piano is prominent, along with soprano sax, clarinet and harp. Now he sees himself moving further toward a vocal style, away from the keyboard. He uses synthesised textures rarely, and listening to his music, you could be forgiven for thinking the synthesiser had passed him by completely. As it turns out, this is far from being the case. Mertens is acquainted with a great arsenal of modern keyboards: JX3P, DX7, Jupiter 8, Jupiter 6, and Prophets 5 and 10 of the synth breed, while on the sampling front, the Mirage, Emulator II and Synclavier II have all passed through his hands.

The Synclavier Mertens dismisses as 'very good but too complicated', and mutters something about a 'bad experience' which he refuses to elaborate on. The EII comes up trumps in his books, but the Mirage doesn't fare so well. 'It's not so good over a wide octave range. I tried multisampling a Steinway piano over three or four octaves and it just didn't sound good enough'. Each to his own. Mertens seems to judge his hi-tech instruments on their ability to sound acoustic, and nothing I can say will change his mind.

So what role do these hi-tech instruments play in Mertens' music if they don't appear on his records? Does he play them in the bath? Well, not exactly.

The Belgian places himself 'in the tradition of written music', so his material is always fully scored out before he enters the studio. He then gets his engineer to program accompaniment parts into a Roland MSQ700 (an MC4 in pre-MIDI days), selecting patches or samples similar to the intended acoustic instrumentation. These parts are then laid down on multitrack tape, after which Mertens gets in his performers to replace them with the 'real thing'. Occasionally he combines samples with acoustic instruments, but only rarely do synths appear in the final mix.

Mertens considers his approach 'a way of working with a limited number of musicians', which slightly puzzles me. But the warning gong has been sounded, and we must draw to a close. Mertens mentions that his technician works a lot with voice expanders now. 'I think these are the future: the keyboard is not needed any more.'

But he is adamant the piano will live on. 'What is it about the piano that you can't get from a synth?' I venture innocently. 'Everything', comes the helpful reply. 'I can take you much further with a piano than I could with any synthesiser. You will trust me much more, and you will go easier along with me tonight while I play on piano. It's much more convincing for you that I play on piano.'

And in the evening, Wim Mertens proves his point. His playing style makes full use of the piano's unique resonant properties, as he eschews the more easily imitated (and more commonplace) percussive approach. As for his Renaissance-style singing, the sheer power of expression it contains is a wonder to behold, as much for its dynamism as its uniqueness.

I keep returning to Mertens' records. It's more than a temporary fascination. His music combines accessibility with substance and a strikingly individual voice which deserves to be more widely heard. And I'm more convinced than ever now. There is life outside of the mainstream, and some of it is breathing in Belgium.