Gospel, according to Virginia Rodrigues

Virginia Rodrigues is a plump black woman in brown high heels and an orange tent dress. She doesn't look like a star. But Caetano Veloso, one of Brazil's most popular singers, has produced her much-admired album Sol Negro, boosting her burgeoning celebrity back home and sparking an international bidding war between David Byrne's Luaka Bop label and Joe Boyd's Hannibal. "I was completely bowled over when I heard her voice," says the victorious Boyd, who chanced upon Sol Negro in his slush-pile. "I just sat there stunned."

Virginia Rodrigues was born and raised in one of the hundreds of favelas (hillside slums) of Salvador de Bahia. Her modest and irregular training took place in the city's Protestant and Catholic churches, and her style, which mixes the clarity of hymns with the strong, nimble rhythms of her country, is unprecedented. Her influences are equally disparate: samba, jazz, opera, masses and spirituals. Underpinning them all is Candomble, the religion of her Nigerian ancestors.

Backed by violin, percussion, guitar and the berimbau, Rodrigues recently made her German debut in Berlin. After a triumphant New York concert (and a rapturous review in the New York Times), she was still nervous. But after a phonetic - and occasionally mispronounced - version of the rousing spiritual "I Wanna Be Ready", she loosened up enough to sweep everyone along on a rapid-fire samba. When, after some jazz-fuelled scatting, she dances again, it's as if mesmerised by the rhythmic intensity of the Candomble drum beat. Three encores later, bouquets of flowers are received with a theatrical bow. "I'd like to thank God," she says in Portugese, "and all the gods."

Known as the New Orleans and the Havana of Brazil, Salvador de Bahia is a place where African rhythms and melodies blend with Portugese influences. Here Rodrigues grew up tripping back and forth between the houses of her favela, listening to the music which always drifted from the radio. Her family displayed little musical flair: her late father was a coffee grinder; her mother a cook, cleaner and vendor in the local market. Her maternal grandparents, however, were staunch Catholics blessed with perfect pitch, who sang canticles, Gregorian chant and, when the mood took them, folk songs.

Rodrigues's voice was a gift. "I started singing at four, when I could barely speak correctly," she said (via a translator, and in between mouthfuls of white bread in an East Berlin restaurant). She went on to sing at parties, school assemblies, weddings and local events. Though not raised a Catholic, she was regularly involved in the traditional church processions. "When I was six I remember astonishing my grandfather's friends," she said, "by whipping off the whole of 'La Diana', this long, complex lament normally reserved for much older women."

Rodrigues left school at 12 and worked as a manicurist. There were no music classes at school, she says, wrapping gold-painted nails around a cup of camomile tea, so what was the point in staying? She read books, bought her own clothes and studied piano in the afternoons until the lessons became too expensive. Then, to the chagrin of her grandfather, she turned to evangelical Protestantism. "The music was prettier, the choir spent more time singing and there was a social side," she explains with a shrug. Later, while seeking employment as a domestic, she began performing regularly on a series of low-budget televised amateur talent shows.

"It was frustrating," she says. "I would come in, this poor black singer, with a prepared piece, and they would say it was too difficult for me." She snorts dismissively. "But they were the ones who didn't know the arrangements, or couldn't find the sheet music." Still, for a while it helped the day job: "One woman who had seen me on TV hired me on the spot. She thought it was so cool that her cook was a singer." The Protestant clerics, however, vehemently disapproved of such moonlighting. At the age of 19, Rodrigues went back to singing can-ticles in a Catholic choir.

The Protestants had also objected to the mysterious Candomble, which Rodrigues had continued to practise. The Catholics, as descendants of Nigerian slaves transported to Brazil by the Portugese, she says, "embrace it because they understand that it's their roots." Rodrigues struggles to find the words to describe the religion, whose rituals involve much drumming, dancing and invocation of deities. "Let's call it energies that flow and fuse - sometimes in a very contained manner, sometimes in a very confused manner. It's very deep, very primordial. Now, if I can't decide on something, I will always lean on Candomble." Rodrigues never performs without first preparing the stage saluting Ogum, her ruling deity. "He actually takes care of roads and streets but, symbolically, he opens the way."

It wasn't until she was cast as a maid in Bye Bye Pelo, a piece about social inequalities performed by a street theatre company, that she was lifted from anonymity. Rodrigues sang Veronica, the same Catholic a capella chant that opened the Berlin show. Caetano Veloso happened to attend a rehearsal. "I heard her singing, and I cried. I was amazed," he said. "I knew she would be a phonographic event of great importance."

Far from offering social commentary, the music on Sol Negro reflects Rodrigues's sophisticated influences. There are literary songs, jazz-blues numbers and folk songs. She calls it "Brazilian gospel". "I know my singing style is very dramatic," she says, raising herself taller in her chair, "but then many of the songs I choose are lamentations. So when people cry, as they regularly do, it's because of the lyrics as well." Her art, as she prefers to call it, is mindful of both her origins and the universality of music. "It is," she grins, "a mixed salad."

Rodrigues is studying bel canto and lyric singing, and has resumed piano lessons. "Brazil is a country in which moulds and patterns are all important. I didn't fit into any of them. I have always had the will and the passion for music, but at the point when Caetano Veloso discovered me I had little hope left. This has all been a very happy surprise."

For Veloso, Sol Negro "is the record Virginia deserves". Given the lack of major new Brazilian stars, it is also one that the country needs. Rodrigues will, with a bit of nudging, admit to accepting the role of ambassador. "I am one of many carriers of many messages," she says carefully, "but I am still what we in Brazil would call an emerging singer." And, she agrees, an unlikely star. "My struggle was complicated by the fact that I am black, I am a woman and I am poor. Three strikes," Rodrigues says, smiling broadly. "But not out."

Virginia Rodrigues: Purcell Room, SE1 (0171 960 4242), Monday.