It was not just bad. It was not-knowing-where-to-look bad. And the man responsible is rapidly becoming public enemy number one in South Africa.

Reggae singer Ras Dumisani mauled, mutilated and murdered the national anthem in a hilariously off-key rendition before South Africa played France in a rugby international last Friday.

Some fans in Toulouse were in fits of laughter, but the Springboks players looked incredulous during the sub-karaoke wailing and later complained that it robbed them of inspiration.

Unfortunately for Dumisani, who was flanked by two bongo players, South Africa takes rugby very seriously. Outraged critics are blaming him for their team's 20-13 defeat in a heated national debate that is escalating in newspapers, radio stations and Facebook, where one group is called "Ban Ras Dumisani From Ever Singing Again".

The South African Rugby Union has written to its French counterpart to complain that Dumisani's tuneless attempt at Nkosi Sikelel' iAfrika ("God Bless Africa" in Xhosa) was "absolutely disrespectful". This is despite his name having been on a shortlist of artists drawn up by the South African embassy in Paris.

Even politicians, normally preoccupied with crime, race and the economy, are piling in with strong opinions. The Congress of the People called Dumisani's rendition a "vocal misfire", saying: "It looked as though it came right out of the blooper reel of a reality TV singing show."

The Young Communist League of South Africa said Dumisani was a "howler of note" and should sing "only in his shower".

The Springboks team were also far from impressed. Player Victor Matfield said: "It was a joke out there. The guys couldn't sing along to it and even the crowd were starting to laugh. It was very disappointing."

But Dumisani, a native of Durban now based in France, denies that he hit the wrong notes and got some of the words wrong. "No one told me they were upset with the singing," he said. "In fact, someone just came up to me and told me how beautifully I had sung. Everyone at the stadium told me I sang well, even after the match. The Nkosi Sikelel' iAfrika has been my tune since I was a baby. How can I not know the words? I am the biggest reggae man in South Africa and the Springboks are my team."

But today, besieged by criticism, Dumisani told a radio talk show that the organisers gave him an "old cordless microphone" and an old monitor, and accused them of "wanting to sabotage" his performance.