This event sums up the international spirit of Manchester's festival. Front of stage are Amadou & Mariam, the blind couple from Mali-turned world music superstars. Backing them, for two nights, are the Beating Wing Orchestra, a Manchester-based group of musicians made up of asylum seekers, migrants and refugees of both sexes from everywhere from Kurdistan to "the Congo, via Ardwick". But the first words we hear are more prosaic. "Are the fans working? asks an official. "It's going to be hot."

Indeed. In their shades, Amadou & Mariam look as cool as Ike and Tina Turner circa 1965, but their euphoric Mali music raises the temperature immediately. The BWO are less an orchestra, more a giant African-funk-rock band, with ingredients as diverse as Bosnian fiddle and Peking operatic wailing. At times, it feels as if you are on a Manchester tram driven by a deranged driver who wants to hurtle around the globe before the start of Coronation Street, which may be the mindset of musical director Arun Ghosh, who we are drily informed was "conceived in Calcutta, bred in Bolton." The music unites the crowd in such a sweaty mess of clapping and dancing that Amadou suggests "fetching some water from the river".

Grinning drummer Pat Mackman baffles everybody with a lengthy speech in which he claims to be a ghost, but makes perfect sense when he refers to "the international language of music." Despite the celebratory vibes, this also seems a subtle but effective political statement. If some of our more rabid rightwingers had their way, many of these people would not be in the country.

Amadou & Mariam play the Roundhouse, London, on 28 July. Box office: 0870 389 1846.