Nobody saw it coming. The success of Iranian art-house cinema must be among the most surprising artistic developments of recent years. Despite the sporadic appearance of Japanese film-makers such as Yasujiro Ozu or Akira Kurosawa, or Indians such as Satyajit Ray, never before have so many distinguished directors emerged from one non-Western nation.

The most prominent is Abbas Kiarostami, the director of luminous, cryptic films such as The Wind Will Carry Us, from 1999, Through The Olive Trees, from 1994, and Taste Of Cherry, the joint winner of the 1997 Palme d'Or at Cannes.

Kiarostami visited the Galway Film Fleadh a fortnight ago to host a director's workshop and, had things gone to plan, speak to The Irish Times. Unfortunately, he was unable to find time, leaving this journalist wandering round in despairing circles like a character in one of his films. Thankfully, we were able to talk with Dr Jamsheed Akrami, Kiarostami's friend and translator and one of the foremost authorities on contemporary Iranian cinema.

An associate professor of communications at William Paterson University in New Jersey, he has been commenting on the subject since his time as a film critic in Iran in the 1970s. Friendly Persuasion: Iranian Cinema After The Revolution, his fascinating documentary from last year, was shown in Galway to much acclaim.

What is often referred to rather glibly as the Iranian new wave actually had its roots as long ago as 1969, with Dariush Mehrjui's film The Cow. As Akrami puts it: "This was the beginning of an alternative cinema, a cinema that is issue oriented, but at the same time is cinematically polished."

Mehrjui's film tells the loosely structured tale of the experiences of a collection of impoverished villagers following the death of their only cow. With its naturalistic ambience and raw humanism, it betrays the influence of Italian neo-realists such as Roberto Rossellini and Vittorio de Sica. It is easy to forget that pre-revolutionary Iran was culturally linked to the West in a way that would be unthinkable now.

For directors such as Mehrjui and the young Kiarostami, these European film-makers proved a significant inspiration. "And then of course there was the French new wave," says Akrami. "The influence of this was in how personal the films were. It was a convergence of these two movements. Socially responsible on the one hand and possessed of a personal vision on the other."

The hiatus caused by the revolution in 1979 led to a trauma for Iranian artists. But it is one of several ironies about this school of film-makers that despite the censorship that comes with post-revolutionary fervour, they emerged creatively stronger.

The story of the director Mohsen Makhmalbaf illustrates the phenomenon. "He was initially such a fundamental believer in Islam that when he would pass a music store he would stick his fingers into his ears, so that he wouldn't commit a sin by listening to this corrupt Western music. He had great faith in the revolution," says Akrami.

Yet in Friendly Persuasion, Makhmalbaf's anger at state censorship sees him distressed almost to the point of tears. "He has ended up being under special scrutiny, because he started off as a devoted Muslim film-maker. His films were very religiously didactic. But what happened, I think, was that the cinema changed him, the medium itself changed him. Everyone was surprised when he made a film like The Pedlar in 1987: a three-part film which showed Iranian society to be like a zoo."

Despite a growing body of work, the world did not really take note until 1995, when Jafar Panahi's The White Balloon won the CamΘra d'Or at Cannes. Scripted by Kiarostami, it is an ideal primer for the new Iranian cinema. It tells the story of a young girl's attempts to avoid losing the money she has been given to buy a goldfish.

Here are the essential components of the best Iranian work: amateur actors, a focus on childhood, a loosely organic structure and, most of all, a delight in unrefined humanity. The actors in The White Balloon jostle forward, eager to be seen in their robust natural state - a welcome contrast to the primped, polished cyborgs that appear in commercial American cinema.

Meanwhile, Kiarostami had been developing his now familiar elliptical directing style. His early films, many made for a state educational body he headed, tended to focus on children and had a relatively formal structure. Now they became increasingly slippery. Close Up, from 1990, told the true story of a young man who impersonated Makhmalbaf, flirting with documentary techniques in the process. Through The Olive Trees began with a sequence in which the director of a film within the film selected one of the actresses who would appear in the movie - that's Kiarostami's, not the fictional director's. Are you still with us?

Almost all of Taste Of Cherry sees the protagonist driving round the desert asking passers-by to assist in his suicide. Why does he want to die? Does he succeed? We never find out.

This ambiguity, the things left unsaid, is the aspect of the director's work most often singled out as his defining characteristic. "This departure from conventional narrative is important," says Akrami. "He sees cinema as something that should be more like art forms other than literature. In literature, storytelling is required. But a painting, a piece of music, these don't necessarily tell you a story. They allow you to . . . make interpretations."

This brand of equivocal cinema, with its ritualistic repetitions, is not to everyone's taste. Many find its longueurs neuralgic. In an interview in Friendly Persuasion, Kiarostami suggests with a straight face that he may be among their number. He says he likes the sort of films that allow him a "nice nap".

I suggest to Akrami that he must be joking. "I think he is serious," he says, laughing. "There is a film, which I'm not going to name, which he helped win a major award at a festival. Yet he admitted to me that he had slept through parts of it. But the quiet of the film allowed him meditation and, maybe as part of that, a nice nap."

The pre-eminence of the drowsy maestro allows Western critics to characterise Iranian cinema as homogenous. This is too easy. "There are many aspects to Iranian cinema," says Akrami. "We do have the Kiarostami type of cinema, which every Iranian is proud of, even those who have no idea what his films are about. But we also have a type of neo-realist film that is closer to Iranian cinema before the revolution; movies that tackle social issues like Panahi's The Circle from last year, which won the top award at Venice but is nonetheless banned in Iran. And we still have a strong focus on children's stories."

These include Majid Majidi's heart-rending dramas Children Of Heaven, from 1997, and The Colour Of Paradise, from 1999, which are among the finest recent films from anywhere in the world.

Perhaps the most fascinating paradox about recent Iranian cinema concerns the role of women. Despite a regime that severely restricts women's freedom of expression, the country has a disproportionately large number of female film-makers, most notably Makhmalbaf's daughter Samira, whose film Blackboards has been screened with great success internationally.

This all heaps a heavy burden of critical expectation on Iran's young directors. But Akrami, who is curating a festival of new Iranian cinema that will tour America, is optimistic. "What is remarkable is that, right now, four generations of Iranian cinema are working side by side. You have the first generation: Kiarostami, for example; the second with Mohsen Makhmalbaf; the third with Majid Majidi and, last year, several Iranian films won best-first-film awards all over the world. In Montreal, for example, another woman film-maker, Maryam Shahriar, won for Daughters Of The Sun. I foresee a very bright future."

Let's hope so. We have rarely been as confounded by anything in cinema as we have been by these enigmatic film-makers. We await the fifth generation with enthusiasm.

The Circle by Jafar Panahi will be shown at the Irish Film Centre, Dublin, in September