Park Chan-Wook's provocative and unsettling thrillers have made him one of the leading lights of southeast Asian cinema. The mild-mannered Korean tells Michael Dwyer that violence for its own sake doesn't interest him - and that revenge is a dish best served with a helping of humour.

JUST as many comic actors and writers prove to be resolutely serious when they give interviews, it also happens that the directors of some of the edgiest, most disturbing psychodramas - David Lynch, David Fincher - come across as polite, quiet-spoken and even entirely normal when talking up their movies.

And then there's Park Chan-wook, the South Korean who turned heads with the mindbending Oldboy, a bravura exercise in sheer cinematic style. Oldboy dealt with the fate of a loud-mouthed drunk abducted and held in solitary confinement for 15 years. The thoroughly unsettling consequences included live octopus consumption, bloody torture by dentistry, and twisted narrative revelations.

Impeccably dressed all in black, Park smiles serenely at the recitation of those startling elements in his movie.

Now 42, Park started out as a film critic after he graduated from Sogang University with a degree in philosophy, but a college screening of Vertigo convinced him that his vocation was as a director.

"I started to write about films for a number of reasons, and one was that I needed the money," he says, speaking through an interpreter. "Even after I started directing my own films, I still had to do it because my early films were not successful and I still needed the money. So, instead of making films, which is what I wanted to do, I was spending more time writing about the films made by other directors."

Park's first two films - The Moon Is the Sun's Dream (1992) and A Trio (1997) failed to register on the radar with audiences or critics. But in 2000, his third film, JSA (Joint Security Area), a tense thriller set along the demilitarised zone between North and South Korea, broke box-office records and made Park's name on the international festival circuit.

Having experienced the film industry from two different sides, as a critic and as a director, Park says he remains mystified as to what audiences will respond to, positively or negatively. "I rely on one person's judgement," he says. "I discuss every detail with my wife, from the beginning of a screenplay to the music I use after the film is finished shooting. She comes up with some very interesting ideas and insights."

Park followed JSA with the moody, hard-boiled class conflict drama Sympathy for Mr Vengeance, which marked the beginning of his revenge trilogy that continued with Oldboy and concludes on Lady Vengeance. However, Park says, this series was not originally conceived as a trilogy.

"After Sympathy for Mr Vengeance was released in Korea, there was a press conference there to announce that Oldboy was going into production. When the journalists were told that it was another film about vengeance, they asked why I was returning to that theme. I said it was something that interested me for many reasons, and then I impulsively said I might make a third film on the subject."

Anyone familiar with Oldboy will know not to expect an easy, passive experience from Lady Vengeance. The protagonist, Lee Geum-ja, is introduced as a notorious criminal jailed at the age of 18 for abducting and killing a child, and released after 13 years as an apparently model prisoner, although we later learn that she discreetly added to her murder toll behind bars. We also get to know her cellmates, one of them an exceptionally demanding lesbian imprisoned for murdering her husband and his mistress - and eating them. There is even more daunting imagery ahead, as Lee gets down to the movie's agenda of exacting sadistically protracted vengeance on the real villain of this challenging, eerily compelling psychodrama.

"I wanted the third film to deal with a female character," Park says. "My inspiration for the film came from an incident about 10 years ago in Korea. There was an abduction of a child and the culprit was a pregnant woman. People were stunned that someone who was pregnant could steal somebody else's child. That triggered my ideas for this film, as I tried to understand why that pregnant woman did what she did."

It was not just the content of Lady Vengeance that jolted audiences in South Korea, however, but that Park chose one of the most popular and ostensibly wholesome actresses in the country for the leading role. Lee Young-ae is known all over Asia for a TV soap opera, The Jewel in the Palace, in which she plays a cook of humble origins employed at the imperial palace of the Chosun dynasty in the early 17th century. The series not only made her a star, but one of Korean television's most popular cooks.

"I had worked with her before on JSA, in which she played a Swedish army major of Korean descent," says Park, "but very many people in Korea found it shocking to see her in Lady Vengeance because they had formed this image of her, and this film shattered that image for them."

Asked to explain his evident fascination with revenge as a theme, and why audiences are drawn to it, Park says: "Like many people who want to see those films, I have never fought back when someone has done something wrong to me. I have never been in a fight with anyone, so this has all been restrained and it gets a release when I see films dealing with vengeance. I'm sure I'm not alone in having those feelings, but of course it is more complicated than that.

"I also want my films to show the consequences of violence and revenge. In Lady Vengeance, my ambition was for the audience to follow this woman on her journey for revenge and to share her feelings as she experiences them. A very important part of that is the feeling of emptiness she has towards the end of the film, after all that has happened. I wanted the film to be realistic in every respect and to reflect life as it really is."

Does Park take pleasure from playing with the minds of his audience, as in the last act of Oldboy, with its shocking revelation? "I won't say that I enjoy disturbing the mind of the viewer, but in Oldboy and in Lady Vengeance, it was a necessary part of telling the story. To me, it is also important to have some humour in my films. If all I'm going to show are heavy scenes, the audience will only feel negative emotions, but if there is humour there as well, it gives the audience a sense of detachment and the room to think about the film and to form their own interpretation."

For a director who cites seeing Vertigo as one of the formative experiences of his life, it follows that Park has been heavily influenced by Hitchcock, not least in how he achieves much of what is most unsettling in his own movies, employing his powers of suggestion.

"Violence for its own sake doesn't interest me," he says. "I am much more interested in creating psychological tension, and I think the most effective way of doing that is not to be explicit. The viewers imagine it for themselves, which draws them deeper into the film and into the minds of its characters. They understand the characters better and have to think about why they behave in the way they do.

"Ever since I was a film critic, I have admired films that encourage the viewer to think while they are watching and listening to what is happening on the screen. When I have to use some violence in a film, it is because the film will go on to deal with the consequences of that violence. And if the violence is too extreme, the audience will just turn away."

Park has several ideas in mind for his next movie, and he's reluctant to give much away at this stage, although he says with another serene smile that it could well be sweet and light and romantic. "That may be a challenge," he says.

Special thanks to Sonhi Kim, the interpreter for this interview. Lady Vengeance opens next Friday at Cineworld and the Irish Film Institute, Dublin. To coincide with the release, the IFI will screen Sympathy for Mr Vengeance on February 25th and Oldboy on February 26th