We're sitting in a little breakfast place in downtown New York and Gael García Bernal is talking breathlessly about the disastrous effects of globalisation on the rural areas of his home country. Two days earlier, the actor flew to New York from Hong Kong, where he spent ten chaotic days as an Oxfam representative at a summit of the World Trade Organisation. Last night, he was knocking back the drinks and dancing into the small hours at a party in Greenwich Village. Tomorrow, he'll fly home to Mexico to prepare for his first gig behind the camera as a director. His talk is full of passion. His thoughts dart from politics to film to women and back to politics.

'The people who will be affected will be the poor people,' he says, dissecting the future of global trade. 'The countries who will be fucked up will be the poor countries. It's going to lead to civil wars.'

Bernal first grabbed the attention of the world's art-house film crowd in 2000 in Alejandro González Iñárritu's 'Amores Perros', an extreme story of three lives that collide around a car crash in Mexico City. He was 21, and the film turned him into hot property in Mexico.

The next year, he made the sexually charged road-movie 'Y Tu Mamá También', which confirmed him, alongside his old mate and co-star Diego Luna, as Mexico's most in-demand and best-known young actor.

Suddenly, he was the talk of the world's independent film scene. Here was a pin-up with brains and good taste. No wonder there were queues around the block when he turned up at last year's London Film Festival.

Since then, he's played Che Guevara for Brazilian filmmaker Walter Salles in 'The Motorcycle Diaries'; a beautiful cross-dresser for the Spanish auteur Pedro Almodóvar in 'Bad Education'; and a romantic dreamer opposite Charlotte Gainsbourg in French director Michel Gondry's latest mind-warp of a movie, 'The Science of Sleep' (which premiered at Sundance in January). It's an impressive roll-call of collaborators – and not a dodgy Hollywood picture in sight.

'I think Tijuana is the closest I've ever got to Hollywood,' Bernal jokes as we talk about the three months he recently spent on location in the notorious Mexican border town for Alejandro González Iñárritu's latest film, 'Babel'. 'It sounds like a really bad tragedy, doesn't it? "The Closest I Ever Got To Hollywood Was Tijuana"!'

The more you speak to Bernal, the more time you spend in his company, the more you understand that there's something unusual about this 27-year-old actor. There's a refreshing, old-fashioned seriousness to the way he approaches life and work. He#s engaged – politically, culturally, socially – in a way that isn't awkward or mannered. He's hungry to learn, to work with the right people, to do the right thing, to make a difference. If all this makes him sound a little earnest, it shouldn't. There's a natural, confident ease to his commitment to cinema, politics and the world about him.

It's an engagement that's thrown into sharp relief when we talk about his move over to London and to drama school at the age of 17. At first, he was shocked by this country's apathy towards politics and culture. As an outsider, he expected the Rolling Stones, the Marquee Club and a thriving art-house cinema scene. What he discovered were the Spice Girls, 'Lock, Stock...' and fellow students who would rather down pints than watch films.

'I found this difficult coming from Mexico,' Bernal explains. 'In Mexico, there's the feeling that everything you do has a political complexity, you know? Which it does. Also, I think my attitude had something to do with my family. They work in the theatre, underground theatre, so maybe I was pretentious in that sense – or snobbish perhaps.'

Bernal's teenage years coincided with a tumultuous time in Mexican history. The country was emerging from what he labels 'an old tyrant democracy'.The Zapatista movement in Chiapas was rising up against the government. Street demonstrations were part of everyday life. Like many kids of his age, he was swept up by the energy and sheer excitement of the capital's mass support for the Zapatistas.

'That movement polarised the country, but it also united a lot of people,' Bernal recalls. 'We helped to stop the war. It felt that whatever we did would count. Something like a million and a half people demonstrated every day when the war started between the government and the guerrillas.

'I was very involved. I helped with sending food, writing and reading about the situation, and demonstrating about it on the marches. It was great. I was young, and it was fun. And I've got to say, I met my first girlfriend – my first real girlfriend – there as well. It was a great place to meet girls!'

Sex and politics. There's nothing po-faced about Bernal's political engagement. It's wrapped up in movies, fun, friendships, music, travel, theatre and family. There's something pleasing and bohemian about his world view. In Europe and North America, too few people believe that protest – let alone art – can make a difference. Bernal would get along fine in Paris circa '68.

Which helps explain why Bernal spent the past ten days at the WTO summit in Hong Kong. In Hollywood, political engagement more often than not means quick, loud gestures and red faces for all concerned. Bernal's commitment is more steady, more regular, more quiet. He attended the mass protests at the G8 summit in Edinburgh last year on the same weekend that Madonna and Elton et al performed very publicly at the Live 8 concert in Hyde Park. In Hong Kong, he sat diligently in meeting after meeting at the WTO summit, discussing ideas, presenting case studies, assisting grander delegates such as Mary Robinson, the ex-president of Ireland (or 'La Presidenta!' as Bernal calls her, laughing). Before travelling to Hong Kong, he spent time in the Chiapas region of Mexico, discovering for himself the effects that free trade is having on local maize and coffee producers.

Such independent thinking is obvious in Bernal's attitude to films and filmmaking. He's happier on the margins, where the real ideas lie. It's worth contrasting his career with those of younger actors of a similar stature from the States – those who one minute are hailed as the saviours of independent cinema and the next are slipping into 'Spider-Man' suits or getting cosy in 'King Kong's computer-generated fur. It's easier to say yes than it is to say no – the reply Bernal has so far given to approaches from Hollywood.

The screenwriter Milo Addica (who wrote 'Monster's Ball'and 'Birth') tells a good story about how Bernal came to land the lead role in 'The King', the independent American movie that British director James Marsh shot in late 2004 and that will be released here next month. Bernal plays Elvis Valderez, a young American with a Mexican mother, who leaves the navy and goes in search of his father, a Baptist preacher (William Hurt) who he never knew. It's a search that has terrible consequences for all involved.

Many American actors considered Bernal's role in 'The King'. They read Addica's script, they liked it, but, as the writer recalls, they ultimately backed off for what he sneeringly terms 'moral reasons'. They didn't like the film's violence or the ambiguity of a lead character, at first a hero, who commits a horrific act. Bernal, on the other hand, leapt at the chance to make the film. Spot the difference. Bernal has balls. The others have 'profiles'.

'We went to a number of young actors, all of which you know and I won't name names,' Addica goes on. 'They all liked the script but, to all intents and purposes, were concerned with the audience perception of themselves. They wanted changes made to accommodate how the audience would perceive them. Of course, when you pay an actor $20 million he will do an Irish jig on the table for you. He doesn't give a flying fuck.'

Bernal's attitude towards cinema is rooted in Mexico and he is inspired by real stories and the struggle familiar
to his countrymen to get things done.

He says that making 'The Motorcycle Diaries', for which he travelled through Argentina, Peru and Mexico, reaffirmed his commitment to Latin America and Latin American cinema. Earlier this year, he set up a production company, Canana Films, in Mexico City in partnership with friend and actor Diego Luna, and in February they launched a travelling documentary festival that began in Mexico City and stopped off at 16 towns across the country. Right now, Bernal is back in Mexico and shooting his first film as a director: 'Défecit' is a drama that explores enduring class divisions in his country.

Emotionally, Bernal invests a huge amount in everything he does. You can't imagine him coasting through a project; he's too sensitive, he cares too much. He says that usually he wants to become friends with his directors – whether they like it or not, he adds, joking.

'That was the best thing about all these films, on a very personal level, to get to know these people. And I really get emotional about that. Many people have explained their ideas of what cinema is, but so far to me the best definition is that cinema is further proof, further affirmation that fiction can move people more than reality, more than the facts. Also, that in the process of making it you get to travel and make friends.'

We walk around the corner and back to the hotel, still talking about films, Mexico, London and New York, before saying goodbye in the lift. Bernal has two further, urgent meetings today. The first is at the local cinema, where he plans to catch the Tommy Lee Jones-directed 'The Three Burials of Melquiades Estrada', a superb film written by his fellow countryman Guillermo Arriaga, the writer of 'Amores Perros' and '21 Grams'. The second is with a TV set in a bar somewhere. His favourite football team is playing in a cup final tonight. He wouldn't miss it for the world. The revolution rolls on.

'The King' opens on May 19. 'The Science of Sleep' opens on July 28.

Source: Time Out London