Having conquered most of the ancient world in Alexander, Colin Farrell turns to the New World in Terrence Malick's latest epic. Michael Dwyer talks to the A-list party monster about working for Oliver Stone, playing James Bond - and Ireland's smoking ban.

It's party time in Los Angeles, and here is our host, the legendary hellraiser Colin Farrell. We're in his luxurious penthouse suite at the St Regis Hotel in Century City, where the view from the spacious balcony is spectacular - miles of illuminated skyscrapers apparently stretching into infinity.

Here come some of the guests - party boys Val Kilmer and Oliver Stone, followed by the more sedate figure of Collateral director Michael Mann, who's wooing Farrell to co-star with Jamie Foxx as Crockett and Tubbs in Mann's $120 million movie of Miami Vice, which starts shooting in April.

The champagne corks are popping, and the scene might appear to be set for a Bacchanalian orgy of booze, drugs and lapdancers, affirming the myths of the rock 'n' roll, no-holds-barred Colin Farrell lifestyle as feverishly chronicled day after day in the tabloids.

Dream on. In fact, the only remotely illicit behaviour on view is our host using a saucer to put out his cigarettes in this ashtray-free penthouse.

Colin has a babe in his arms, all right, but it's his 15-month-old son James, who resembles him closely and has a shock of brown hair. The party is for the birthday of Colin's sister Claudine, who doubles as his personal assistant as he tours the world, making and promoting movies. Their brother Eamonn, is there, too. The mood is laid-back as we tuck into birthday cake and sip champagne as night falls on Los Angeles.

Colin had spent the day doing interviews, in which he was asked repeatedly about his blond look for Alexander. "I gave them all my stock answer," he grins, "that as a blond, I had more fun." And he had to explain over and over why there are so many Irish accents in the movie. "People seem to have an idea that anything that is classical or historical, or a Greek tragedy, for example, should be cast with English actors speaking RP - received pronunciation English. If we were to go all the way and be accurate about it, we should all have been speaking ancient Greek or Macedonian or Persian, and we weren't going to be as specific as that.

"But we had a lot of Irish and Scottish actors in the film, with me, an Irish actor playing Alexander. Robin Lane Fox, the Oxford scholar who was the historical adviser on the film, suggested all the Macedonians would speak in a Celtic-sounding dialect, and that the characters from the southern Greek states would speak with a more English-sounding accent.

"That seemed to be the closest way to capture that relationship between the two peoples - the Greeks, who were the educators and the philosophers of the time, and the Macedonians who were goat-herders and regarded by the Greeks as tribal people akin to being savages. It was not unlike the relationship between Ireland and England at various stages, you know."

There are so many Irish actors in the movie because Farrell persuaded Oliver Stone to include Dublin on his casting tour. "I knew he was casting in Los Angeles, New York and London, so I told him, 'You're a smart man and you'd be a fucking fool if you don't stop over in Dublin and do some casting there'. I had no idea that he would cast as many Irish actors as he did, and that Alexander would have such a bunch of paddies in his army! It was great to see a fine actor like John Kavanagh getting such a strong part in the film and he's brilliant in it."

Was Stone the tough taskmaster he is reputed to be? "Yeah, he was definitely the hardest fucker I've worked for, and the most demanding," Farrell says. "That was no shock because I talked to some people who had worked with him before. But if he ever wanted to work with me again, I wouldn't even ask for a script. I'd just say yes.

"He's a bull of a man. He's very raw. As articulate as he is, he's a messer as well. I love the man, though. It was great to work with him, to watch him dance across the set and to see how focussed he is and how intense and aggressive he gets as he pursues what he wants. I was on the receiving end of that sometimes, and he's brutally honest. He could come up to me after a take and say, 'That was terrible, that was fucking terrible. I can't print a second of that.'

"Then again, if you did something he thought was great, he'd tell you that you were a fucking genius."

Farrell notes that the cast and crew of the movie probably saw as much of the world as Alexander the Great on his own military campaigns.

"Of course, we had airplanes, but it was still a long, tiring shoot. First there was the training, culminating in three weeks of boot camp under the strict supervision of Capt Dale Dye, a professional soldier who has worked on six films with Oliver Stone. He's the pioneer of this intense boot camp experience for any films that are supposed to be reflective of war or soldiers' lives.

"He's great, Captain Dye, but he's mental. He took us through this incredible experience - 170 men camping in the desert for three weeks. We got up every morning at six or seven and went for a long jog. We had physical training when we got back. Lunch was peanuts and pretzels and a little bit of fruit. We didn't eat again until around 7.30 that night and the food was usually some crap pasta.

"But I loved the whole experience. I lapped it up. It brought us all together in this collective experience with all these strangers. Anyhow, we all knew that in a few weeks we'd be back in our hotel rooms again."

Farrell insisted on performing most of his own stunts in the movie. "I did it because it was fun. Man, to get a chance to do shit you wouldn't get to do in your everyday life. It was fairly scary at times, especially when my horse goes up on two legs when I'm up against this Indian on his elephant. I came off a few times, and one time the horse landed on me and mucked me about a bit.

"I still can't believe they actually let me do as much as I did, because you're so over-protected as an actor these days. I felt it was important that the audience would know that was me up there. I didn't want it look like we were using a stuntman and then cutting away to a close-up of me sitting on a fucking barrel or something."

Farrell had a six-week break after finishing Alexander. "I spent most of my time off hanging out in Los Angeles with the young fella," he says, "and learning to type because I was getting ready to play a writer in Ask the Dust." That film was shot in South Africa, although it's set in Los Angeles during the 1930s. Directed by Robert Towne, the Oscar-winning screenwriter of Chinatown, it features Farrell as Arturo Bandini, an Italian who arrives in Hollywood hoping to land a writing career, and he meets a fiery Mexican played by Salma Hayek.

Just 11 days after finishing that, Farrell started work on yet another movie in the US, this time in Virginia for The New World, the new film from Terrence Malick, the gifted director of Badlands, Days of Heaven and The Thin Red Line. Farrell stars as 17th-century explorer John Smith. The role called for him to grow a big, bushy beard, which he shaved off as soon the shoot finished, a few days before we met in Los Angeles.

"I looked like fucking Charlie Manson," he laughs. "We spent three months in Virginia, which is a strange place, I can tell you, but at least you could have a pint and a cigarette in a bar there.

"I still can't get my head around the smoking ban in Ireland. It's like the Prohibition era now, isn't it? I was back recently and it's frustrating as hell. It's better for my health, I know, but I really feel sorry for these old fellas who've worked hard all their fucking lives and there they are standing outside the pub in the rain to have a cigarette."

When we met, Farrell was bemused by all the media speculation that he might be the next James Bond. "Pierce Brosnan said something about that when he was in Dublin and then it was all overthe papers the next day. That's mad, isn't it? And you know, if I did play James Bond, it would fucking kill me, man. God knows, there's nothing wrong with playing James Bond, but it would be just senseless for me to do it."

Farrell is getting accustomed to seeing his own utterances flashed around the world within 24 hours, as was the case when he was quoted in a recent GQ cover story as saying that he had smoked heroin a couple of times.

"The worst was at home when all that stuff was in the papers," he says. "I'm a bit too long in the tooth not to realise that my words will be read all over the place, but I don't think of it in those terms when I'm doing an interview. I just feel like having a chat, and sometimes I can be misquoted or a bit of a sentence is chopped off, or something is taken out of context.

"People expect a certain persona, I guess - this 'bad boy' label that's been stuck on me, whatever that means. Anyhow, I'm looking forward to going back home for two weeks at Christmas and I'll be able to bring the young fella home with me. Dublin is still very much my home. I don't have a house anywhere else."

Now 28 and with a dozen starring roles to his credit, Farrell has come a very long way in the five years since he played Danny Byrne in Ballykissangel. "When I was nine or 10, I dreamed of being a WWF wrestler," he says, "and then I wanted to be a footballer for years, but as soon as I started acting, I loved it but I had no illusions. If you ever had big dreams of stardom, you would lose them very quickly after going for auditions and getting turned down. I did loads of auditions and I didn't get called back.

"I still get giddy at all the people I get to work with, and I'm still enjoying the work and enjoying life too much that I don't feel like I've done that much. But if you told me five years ago that all this was going to happen to me, I'd have thought you had too much to drink and I'd have ordered you a taxi."

Alexander has its Irish première on January 6th and goes on release here the next day