South African rugby fans' anger mounted yesterday at an off-key reggae singer who "butchered" their national anthem before the Springboks' Test match defeat to France at the weekend.

The South African Rugby Union yesterday wrote to its French counterpart expressing the nation's dismay at the performance before Friday night's match in Toulouse by an artist known as Ras Dumisani.

"As a union we were shocked and horrified by the rendition of the anthem, and I contacted the French Federation on Saturday morning to express our very grave concerns," said the union's president Oregan Hoskins.

Dumisani told Talk Radio 702 that he blamed the equipment for the poor sound, insisting that he had "sung beautifully", but that did little to douse the public outrage at his off-key performance of the four-language anthem.

Rugby fans have already filled websites with their anger, and a Facebook group "Ban Ras Dumisani from ever singing again" won 600 members just hours after opening.

Much of the blame for the debacle from South Africans was being laid at the feet of the French rugby authorities but French team manager Jo Maso said the choice of singer at each game was made by the visiting team's diplomatic staff.

"Every time we welcome a foreign side, we ask the embassy to propose people for the national anthems," said Maso.

"It's the South African embassy that put forward this man."