Playing a lap dancer in her latest movie, Closer, may be the sexiest part to date for actress Natalie Portman but, as she tells Steve Pratt, she doesn't feel she's grown up yet.

Still only 23, Natalie Portman has a film career stretching back ten years. While playing a lap dancer in her latest movie, Closer, ranks as her sexiest part to date, she doesn't view it as her breakthrough adult role.

"I don't really feel like an adult yet myself, so I don't really think I can play adults," she says. "I think it's always a proportion, adult to child within you, and even when you're 85 you're still going to have that proportion. It changes with mood and time, it's an arbitrary distinction."

You can tell from those few words that Portman - who made her screen debut as a 12-year-old orphan taken under the wing of a tough hit man in Luc Besson's Leon - isn't your ordinary young American actress. Despite a busy screen career, she's combined being a psychology student at Harvard University with making movies such as Beautiful Girls, Anywhere But Here, Where The Heart Is and, most famously, playing the young Queen Padme Amidala in the prequel trilogy of the Star Wars saga.

In the film of Patrick Marber's award-winning play, Closer, she more than holds her own against Julia Roberts, Jude Law and Clive Owen. It's the most sexual role to date for Portman who, when she was younger, turned down the title role in Adrian Lyne's Lolita because of the subject matter.

Although she strips in Closer, audiences won't see too much bare flesh. A scene showing her lap dancing topless was shot but didn't make the final cut after she and director Mike Nichols decided it was superfluous.

The film charts the interconnected love lives of four people in London. Portman's character Alice is the youngest of the quartet. It was the writing that appealedl to her. "It deals with the way people often are in relationships, which is what everyone encounters at that age. This can be a big shock after your sweet high school relationships when people become pretty horrible," she says.

"Alice completely creates herself when she comes to London, yet she also has this childlike quality. She's really honest and direct in her feelings, which distinguishes her from the other characters."

The cruelty the foursome inflict on each other was as unsettling for the actors to film as it is for audiences to watch. "Some of the things were really hard to do to each other, especially because we got along well and liked each other a lot. To be really awful to each other was very difficult at times."

She was helped by her close personal relationship with 73-year-old Nichols, who directed her in the New York Shakespeare Festival production of Chekhov's The Seagull, alongside Meryl Streep. "It was amazing to work with someone who is one of my best friends," she says.

"If I have a problem with a boyfriend or life or decisions, he's the one I go running to. He's my mentor and the father I can talk to about boys because he's not actually my father."

Closer comes hot on the heels of her starring role in Garden State, written, directed and starring Scrubs star Zach Braff. The film doesn't really fit into any genre. "Movies now are so often made to mimic other successful movies - the romantic comedy, the thriller, the action movie - which are so formulaic that you can guess the ending after the first five minutes. So it was nice to see something like this that was much messier, like life, that doesn't fit into any category, that doesn't go with anything we've seen before. It just has these unique experiences and unique characters."

Braff and co-star Peter Sarsgaard visited her at university one weekend and they all went out and partied together as a way of getting to know each other. "That's a great way to start out because it breaks down all barriers and we kept that sort of mood on set. There was very much a party atmosphere, like we were joking and hanging out. You feel that in the film, that there was this sense of friends being with each other."

Portman feels that working in the summer break from university was the best way to handle her career.

"I never worked during the school year, so kept the same pattern that I had done at school," she says. "To be an actor you have to be a person who's engaged in the world, whether that's through school, travel or meeting people and listening to them and learning about peoples' lives. That's the most important thing. You're trying to imagine other peoples' lives and where imagination takes you. Having knowledge and first hand experience can really feed that imagination."

Portman's transition from child actress to adult is going well. She points out that her generation of female actors is largely made up of people who started acting as children. "If you look at Kirsten Dunst, Scarlett Johansson, Christina Ricci, Claire Danes... we all started out when we were 11 or 12. I don't know what it is about our generation, but I obviously have some good peers and we keep pushing each other, I guess."

Later this year she'll been seen in the latest Star Wars instalment, Revenge Of The Sith, and acknowledges that doing the fantasy stuff is the most like being a child that she's ever experienced in acting.

"It's like taking the old refrigerator box and pretending it's your space ship because you're literally working with nothing, pretending that it's the most outrageous thing. One of the interesting things is that we all have our idea of what it will look like but then we see it and it's completely different."

* Closer (15) previews in some cinemas today and goes on general release tomorrow.

Published: 13/01/2005