Independence day

Björk's cry of "Tibet, Tibet" at a recent concert in Shanghai pre-empted the riots in Lhasa and outr

In early March, Björk's world tour promoting her latest album, Volta, reached the International Gymnastics Centre in Shanghai. Fans came to the Olympic venue bearing flags they had made in honour of the singer's latest single, "Declare Independence". The song, a heavy techno anthem with its tongue in cheek, tells listeners to start their own currency, make their own stamp, and to raise their flag "higher, higher!". Björk played the number as her encore and whispered the phrase "Tibet, Tibet" percussively at its raucous climax.

At first, very few people noticed, but in a world where every blogger's testimony can ricochet around the globe in seconds, her words were soon causing shock waves. The Chinese ministry of culture issued a statement about tightening controls on foreign artists, and the culture vice-minister Zhou Heping made a statement dismissing her protest as an individual case.

I met Björk in New York eight days after the Shanghai concert, just before her protest was given fresh resonance as riots broke out in Lhasa, Qinghai and Xiahe. "When I said 'Tibet Tibet', I whispered it three times," she says. "There was no fuss in the room. It happened afterwards on websites. It shows more than anything that China has become the next superpower in the world. And the question is how it's going to deal with western moral issues like freedom of speech.

"[The government] said, 'Björk planned a trip to China with the purpose of political propaganda . . .' and I was like, 'No! It's not true!' It's a question of [them] sensationalising it."

At 42, Björk still looks preternaturally young, the shocking pink satin of her dress lighting up the white walls of her management office. She is entirely unrepentant about her comments, her voice nervous but direct, polite but passionate. "I see what I did as a tiny act. With the Olympics coming up, this was one of a hundred rehearsals for the Chinese people to get communicating with the western world, one example of how there are going to be misunderstandings.

"I'm very curious to see how the Olympic thing is going to happen. I mean, hundreds of thousands of athletes and journalists will be coming and writing about it. What I did is nothing compared to that."

She maintains that she does not see herself as a political person. "Perhaps, after what has happened, people will find that difficult to believe. But I'm still working from an emotional core, and my songs come from private and personal experiences. Even songs like 'Declare Independence', for me, are about humanity and about how one person should not abuse the next one."

In previous interviews, she had said that the song was inspired by Greenland and the Faroe Islands - Iceland's neighbouring territories - and their battles against Danish rule, but equally that it could be about "the girl next door or someone in a terrible marriage". When we meet, she says she hopes that "this political thing doesn't take over. I don't want to be put in this political box."

Politics runs in Björk's family. Her father, Guðmundur Gunnarsson, is leader of the Icelandic Electricians' Union, a nationally known figure in his own right. Her mother, Hildur Rúna Hauksdóttir, protested against the building of the hydroelectric plant at Kárahnjúkar in 2002 by going on hunger strike.

Björk was born in Reykjavik in 1965, and music has always been her life. She released her first album at the age 12, performed as frontwoman for the pop group the Sugarcubes in her early twenties, and became a solo star at 28 when her first album, Debut, was released. Since then she has put out five more studio albums, a remix LP and two soundtracks, written songs for Madonna, and collaborated with the trip-hop guru Tricky, the experimental electronic duo Matmos and the English singer-songwriter Robert Wyatt.

Before the Shanghai declaration, Björk's only political gesture had been an appearance at a Tibetan freedom concert in 1996 just after the release of her second album, Post (1995). She remembers it as being similarly "schizophrenic" in mood to Volta, and she even returned to one of the songs from it, "Army of Me", in 2005. Before visiting the tsunami-stricken Sumatran city of Banda Aceh with Unicef, she posted a message on her website encouraging people to remix the track, and released her favourite 20 versions on a charity album, Army of Me: Remixes and Covers, to raise funds for the region.

That record seems to have sparked off a fire in Björk. Her two albums prior to Volta, Vespertine (2001) and Medulla (2004), were fine-spun records, made in the afterglow of new motherhood. "Volta was very much an album for me where you go out and plant many seeds. It wasn't like an old tree which had been growing for a long time, as Medulla was. It was my Christopher Columbus album - about me going out and looking for new stuff, full of that Newfoundland kind of fickleness."

Volta was eventually released in May 2007 to a hail of acclaim. A hugely adventurous, bombastic explosion of avant-garde pop, it brought Björk back together with Mark Bell, a member of the techno act LFO and her producer on Homogenic (1997), and also merged the talents of the American R'n'B producer Timbaland, the Mercury Prize-winning Antony Hegarty from Antony and the Johnsons, the Malian kora virtuoso Toumani Diabaté, and the Congolese collective Konono No 1. It is a global album that is electronic and danceable but also, as Björk explains, one that is "grounded in the rhythms of the earth".

The singer acknowledges that in the years prior to Volta, she was happy not to think about world issues. "There are time when you're more Buddhist, when you duck [problems]; and there's times when things come at you, and you defend yourself and take them on. It was definitely the right time to take things on." She attributes her politicisation to the Bush regime. "If you'd told me as a teenager that it matters in music-making - or anything you care about - who's the president of the most powerful country in the world, I'd have been, you know, 'Fuck off.' I thought that politics had nothing to do with anything, and that's the point of making things and writing songs: that art is the opposite of that. But you see how people behave, how it affects culture, and you realise it is related."

She has also taken a new interest in feminism, inspired by having a daughter with the art film director Matthew Barney. She had already had a son, 21-year-old Sindri, with her former Sugarcubes bandmate Thor Eldon, but her experience with five-year-old Isadora has been very different. "She started to ask questions, and it made me realise how backwards things have gone for women in the last ten years."

The colourful Earth Mother image on Volta's cover was an empowering concept for her, as was the all-female brass band with which she has toured. She sees her feminism as being of an optimistic sort. "You have to bring up positive stuff or new stuff, and think ahead, rather than being stuck with how wrong gender rights were in the past. That's the only way forward."

In the past couple of years, and since she has been touring with Volta, Björk feels that at last people are waking up to what is wrong with the world. "Suddenly it seems people overall are getting on the right brain hemisphere. People are going: 'The Iraq War was a bad idea' and 'We need to be green'. People are not as conservative and extreme as they were. Two years ago, everything felt really wrong, but now it doesn't."

She sounds like a cultural ambassador, but she is not about to take on any such role. "I can't pretend I can be some adviser to China, can I?" she says. "That would be ridiculous." She smiles calmly and sensibly. "And how can I be? I'm just a musician."

Jude Rogers is editor of www.thelipster.com. Björk's UK tour begins on 11 April

The wisdom of Björk

"I find it very difficult to draw a line between what's sex and what isn't. It can be very, very sexy to drive a car, and completely unsexy to flirt with someone at a bar."

"Choosing between men and women is like choosing between cake and ice cream. You'd be daft not to try both when there are so many different flavours."

"Football is a fertility festival. Eleven sperm trying to get into the egg. I feel sorry for the goalkeeper."