U2 frontman Bono found himself at the centre of another racism row last night as the band kicked off its South African tour.

For the second time in a week, the band was in the limelight for all the wrong reasons after the lead singer appeared to show support for a controversial anti-apartheid song, which includes the words "shoot the Boer" (or "shoot the farmer").

The song prompted sustained debate after the murder of Eugene Terreblanche, a white separatist leader who was hacked to death on his farm, allegedly by two black employees.

Julius Malema, the head of the youth wing of South Africa's ruling African National Congress, was reprimanded last year for singing the song, which was an anti-apartheid anthem in the 1980s.

The song has been labelled "hate speech" by some members of South Africa's white community and the country's highest court is currently considering whether it violates the rights of Afrikaners.

But Bono compared its lyrics to Irish rebel songs about the IRA.

"I was a kid and I'd sing songs I remember my uncles singing. . . rebel songs about the early days of the Irish Republican Army," he said.

"We sang this and it's fair to say it's folk music. . . as this was the struggle of some people that sang it over some time."

But he cautioned that such music shouldn't be taken out of context.

"Would you want to sing that in a certain community? It's pretty dumb. It's about where and when you sing those songs," he said.

The comments, made to a South African newspaper, caused a storm of controversy about whether Bono was coming out in support for the firebrand leader of the ANC's youth league, Julius Malema.

Mr Malema has been taken to court by an Afrikaner lobby group after singing the song at political rallies.

The report immediately reopened debate on South African social networks and radio talk shows.

Steve Hofmeyr, a popular Afrikaans musician, told his Twitter followers he had thrown tickets worth more than €475 for U2's concert in Johannesburg into a river in protest.

A spokesman for the band insisted that Bono's comments were quoted out of context and that he was not referring to the "kill the farmer" song.

This latest row has come just days after U2 manager Paul McGuinness dismissed allegations that the band was failing to employ enough local black workers during its two-date tour of South Africa.

The South African Roadies Association had threatened to picket U2's concert in Johannesburg to highlight what it said was the refusal of big acts to employ black crew.