The role of French secret service agent Philippe Roache in Godzilla was tailor-made for Jean Reno. Killers are easy, he tells Charlie English

It is easy to spot Jean Reno's arrival in a film. The face, with its baggy-eyed, shagged-out look, is that of a man who has spent 25 years committing atrocities with the French Foreign Legion. He is probably walking too fast, silent-movie pace. He will be wearing a long trenchcoat and carrying a bag - a clown late for a birthday party, lugging his tricks with him. Only, when Reno opens his bag, it is full of acid or a huge, snap-together rifle.

It's a send-up: he swirls into Luc Besson's 1990 film Nikita, swiftly acid-baths somebody, gets shot, drives through a wall, delivers a few lines ("I never leave a job unfinished"), then dies. In Leon, again in the "cleaner" role that Tarantino borrowed straight for Pulp Fiction, he brings ruthless efficiency to the daily routine of moving a houseplant around in his flat. Eric Morecambe, licensed to kill.

You can do killers? "Yuh," he says.

Reno doesn't look like a killer now. His round glasses hide the baggy eyes. He is attractive, sometimes self-deprecating. He laughs a lot, often at things he has difficulty communicating in English. Women like him, he says, because he looks responsible: "Like I'm not a crazy guy who's going to do anything to be a star." He has just been in the bathroom, speaking on the mobile to his second wife, who is expecting his fourth child any day. He toys with a cigarette for 10 minutes before lighting it and occasionally dragging on it. His French accent is heavy, and when his English fails, he speaks a mixture of the two, painting in the idea, then turns for confirmation to Cameron, his dialogue coach, who sits in the corner of the room. "My wife called me to say, 'You forget me, huh? You don't call me?' I said we arrived at the weekend, we had a one-hour delay, then we took the train, then we start the interviews ... She's in Paris.

"Would you like a drink? Water? Wine? Some steak? With chips? Some salade?" Reno's father was 13 when he left Spain with his Republican parents, on the run from the civil war ("That," says Reno with distaste, "was a really dirty war"). They arrived in the French protectorate of Morocco, where his father found work as a linotypist on a newspaper, and Jean, the eldest of two children, was born in July 1948. He grew up there, in the calm time before the storms that would change colonial North Africa for good.

"Casablanca was the second port of Africa, after Dakar. One million and a half people. Americans, English people, German, Dutch, Spanish, Italians working there. And it was easy. There was no winter. Easy.

"There were five of us from Morocco - five very good friends. Two Jewish - Jacques and Yves. Vincent, he's Sicilian. Christian, he's French. The two Jewish were American. I was Spanish at that time. Strange group, huh? Completely different. Not the same likes, not the same taste." It was cheap to live, and for the five friends every day was hot, all the beaches were golden. Then, in 1967, the Six Day War came along. The movement of the Israelis into the Sinai and Old Jerusalem meant Reno and his friends had to move, too. The two Jews were forced to leave Morocco quickly. The Italian left because he had to join the army. Another one left when the bank he worked for moved away.

"That war moved old North Africa - Algeria, Morocco and Tunisia," says Reno, "because the Jewish were the middle class. And if you kick out the middle class, it's no longer the same country. Everybody ended up getting out." Reno left a year later. He wanted to become French, and national service was mandatory for French citizenship. So he signed up for the army, and arrived in Marseille on May 21 1968, the month that found France on the brink of civil war.

"I had no idea about the revolution. We were just looking for women, you know? And what happened we didn't know about. Okay. There was a black flag and a red flag on the railway station, and they put us on the military tracks to Germany. Wow!" When he got there, Reno set out to do as little as he could - to become a shadow, he says. The French army in Germany was full of professional soldiers who had come back from fighting in Algeria and Vietnam ("Commandos. Very cold. Terrible"), and his goal was to avoid them, to avoid the exercises, the shooting, the manoeuvres.

"They saw in my CV that I had been to the national drama school in Casablanca, so they put me by the officer ... I was in charge about the bands, about plays - about things like that. So I avoided most of the soldiering."

He served his term, a year, in which time he became French. He knew that because he began to argue with his father over olive oil - in Spain they use it for cooking, but in France they only use it raw, on salads. All the time he was thinking, "Paris. Theatre." So private first-class Reno went to live the bohemian life of the Parisian drama student. "Paris was fantastic at that time," he says. "Not to work - well, to work a little bit. But going to drama school, being with the women."

He got a few days' work a week, some TV, and in 1972 a part in Costa-Gavras's Clair De Femme, with Yves Montand. He toured Europe with Didier Flamand's theatre company, played in Bertrand Blier's Notre Histoire. "They said it takes 10 years to make it from the moment you arrive in Paris, if you are good. Bon." It took Reno a little longer. In 1981 he teamed up with Luc Besson, the director whose films - Subway, The Big Blue, Nikita, Leon - would take them both to fame and fortune.

"Why did it take off with Luc? Because he likes me and I like him. It's a very special relationship. It's not being gay, nothing sexual, nothing ... body. But I understand him. And I love his defects and I love his qualities, and I think it's the same for him. But we were three - because there was also the composer Eric Serra [who writes music for Besson's films]. We called it the molecule. Very strange, very strange.

"I don't think about who is the most successful now. I don't think like that. I look at him to see if he's becoming a better human being, and he look at me the same. He says to me, "Uh-oh, this is not good for you, huh? Don't do it, huh?" I say, 'Okay.' But maybe I'll do it anyway. Then we laugh. It's quite difficult to be a real friend and not be a weight on the shoulders. Between an actor and director, it's difficult."

In The Big Blue Reno played a free-diver, Jean-Marc Barr's comic rival for Roseanna Arquette's affection. It was his first big starring role, it won international acclaim, and he blew up. He left his first wife and two children to sleep around, to travel the world. He went on a bender for a year and a half.

"Surely but slowly, you go down," he says. "How can I say ... It's like having too much food, so you lose the taste. Too much food, too much fame, too much travel, too much bullshit. That's why, when they're young, most of them - actresses, actors, directors, producers - they go into drugs and they go into drink ... One day, by chance, I noticed a red light going tootootootootoot in my head. I was having a fantastic love story at the time. But it was a love story that was destroying me.

"It's like you find the most difficult way to change yourself, to make yourself to go up 10 levels." He demonstrates a career elevator with his hands. "Big Blue was here, yes? And after The Big Blue I was big box-office, in France and everywhere around the world. And you find something that will hit you, hurt you the maximum. It's like you have to change the shape of your mind. And at the end you are ready to start again. Because in fact your work is to give pleasure - to understand, to translate, to be somebody else. You have enough energy and it's clear, so you cut, finish the love story and you start working. Ouais.

"Then maybe you can accept yourself. Because nobody can understand what fame means." What does it mean? "Suddenly everybody listens to you. Before that, non. 'It's okay, Jean,' they would say, and continue talking when I speak. And now when I speak it's, 'Hohohoho, Jean, fantastique!' And you have to find the right balance. Voila."

Reno is a sex symbol in the slightly unlikely way that Gerard Depardieu is. One woman interviewer described him as "sex on legs". It is partly his openness, partly his ease. Depardieu, he says is different. "He is more an animal than me. More sexual, in fact. No, Gerard is completely different.

"I think women look at me and think, 'This one, he is responsible. This one's trustable.' It's like stability, you know. It's also loneliness. They're lonely. 'Okay,' I say, 'It's like, I'll try not to disappoint you'."

Reno describes Godzilla's director and producer, Roland Emmerich and Dean Devlin, as children, and he likes them for it. They had sat down and watched all Reno's Besson movies, and told him they were going to write a script for him. The result was the part of the French secret service agent Philippe Roache. When he saw it, he thought it was humorous and unpretentious. Shooting, he says, was simple.

He says it is important for him to make a French film for every American one. He dislikes the American star system: "What is a star? You have a lot of secretaries. But you have loneliness. Drugs, wine, women, bof. I don't understand that. And I don't want to. For me it's an agent, a manager, a dialogue coach, who is a friend. I won't go inside that kind of system, you know? I'm too old." Yet he appreciates the actors the American system has made. French cinema is not bad, he says, but it is in a bad mood.

"It is not carrying enough hope. Of course, you need movies to talk about Aids and about anything you want. But sometimes you need hope and you need to make them laugh. When you see The Full Monty, they talk about the unemployed people, but they make them laugh, so it's accepted. But when you start out not wanting to do that from the beginning, it's bad.

"It's difficult for the young - they don't like to play the hero. If you lose what we call the jeune premier, the lover, you lose a big part of movie business. We have no Tom Cruise or Leonardo DiCaprio, which is wrong because you can tell stories through actors like that. The young people want to say, 'Look: I'm young, I'm suffering.' I say, 'No, the audience is suffering.'"

Next month, Reno will be 50, and the group of five Moroccan friends will be together again, in Annecy, by the lake, with their families. "We're gonna have a big feast. Wow! Ohmigod! We five from Casablanca are still together. One is in New York now, another in Milano, another one in the country in France and other one in Paris, and myself. Altogether there will be 50 people … Two days. A little promenade on the boat … things like that. Stupidity. And my sister will sing - because you can't stop my sister from singing."