The saints march in: Philip Sweeney gets into the swing of the Festival of Bahia

If you're pursuing an interest in the Afro-based culture of the northern Brazilian state of Bahia - awakened perhaps by the Olodum's thunderous drumming on Paul Simon's Rhythm of the Saints, or by Margareth Menezes' tour cameo with David Byrne - the one thing not to do right now is go to there. Until 2 July, when the Feast of St John unleashes another prolonged bout of partying in the region, London is where it's at.

The Festival of Bahia, organised by Edna Crepaldi, of the London-based Brazil Contemporary Arts, culminates in an Albert Hall extravaganza on 1 June, featuring the four greats of Bahian popular music - Gilberto Gil, Gaetano Veloso, Gal Costa and Maria Bethania - plus 50 drummers and dancers from Rio's venerable Mangueira samba school.

Crepaldi has been planning the festival for five years, noting the increasing popularity of Bahian music. Bahia's carnival is fast becoming the most prominent in Brazil, while, in Rio, Mangueira has honoured Gil, Veloso, Costa and Bethania - the doces barbaros (sweet barbarians) - in their Mardi Gras marching song and floats. Good enough reason for a modest bash in London.

Things got off to a gentle start last week with the opening of an exhibition by Bahian artists in the Barbican, and the screening of Jana Bokova's sensuous documentary Bahia of All the Saints (BBC 2).

On Saturday, the festival moved up a gear with a performance by the Afro-bloco group Ara Ketu. Some 450 people braved the rain-lashed pavements of Vauxhall, many of them Brazilian and some sufficiently au fait with Bahian fashion to essay the requebro ('swing') dance step, moving their hips from side to side as if taking a promenade along Ipanema's sea-front. On a simple level, Ara Ketu is a good- time dance group and, Brazilians being Brazilians, the place was jumping.

But there is more to Ara Ketu than dance tunes. The Afro-blocos sprung up in the Seventies, a manifestation of the region's African roots-rediscovery movement. Their lyrics speak of the ancestry of Brazil's black population, most of whom arrived as slaves from West and Central Africa, and their drum arrangements borrow from the sacred rhythms of candomble, a religious cult in which drumming is used to encourage possession by the orixas - Yoruba deities or saints.

Of the dozen Afro-blocos, Olodum is the most famous, and their crashing, seething backyard public rehearsals in the old colonial quarter of Pelourinho are the most exciting. Ile Aye is the oldest and purest, but Ara Ketu is the most progressive, having evolved a compact squad combining drums with keyboards, bass, guitar and saxophone to play anywhere from the top of a trio eletrico to a stadium.

In Bahia, Ara Ketu can be seen performing outdoors, with lame-robed fire-juggling dancers lending a circus air to proceedings. Shoe-horned on to the little Vauxhall podium, with their white metal repique, surdo and treme-terra drums (the last means earth-shaker) standing in line on the dance floor, the 11 musicians looked cramped but put on a good show.

Their name - 'People of Ketu' in Yoruba - refers to one of the old kingdoms of the region which is now Nigeria, and many of their songs mention characters such as Elejigbo, a one-time king of Ketu. As with all the Afro- blocos, Ara Ketu's historical research can be a touch theatrical: a member of Olodum once asked me to track down a comic book allegedly called Tutankhamun's Friend at the British Museum for their Egypt-themed carnival gear. Ara Ketu's drum rhythms cannot be argued with though, from the fast, bouncy samba duro - hard samba - to the heavy, loping samba-reggae.

Bahian Afro-religion - always present in Ara Ketu's show - is moving mainstream in Brazil, and the festival also features lectures by two seminal figures in the spread of candomble to the arts elite: the novelist Jorge Amado and the eminent 91-year-old ethnologist Pierre Verger. Not forgetting Gilberto Gil and Gaetano Veloso, who as budding rock stars in the early Seventies spearheaded the most recent wave of popular interest in the subject. Enough, in short, to make Bahia as accessible as Bognor, at least until the end of the month.

Festival hotline: 081-748 0276