President Jacob Zuma's refusal to distance himself from the song "kill the boers, they are rapists", suggested his endorsement of "the incitement to murder fellow South Africans", Democratic Alliance leader Helen Zille said on Friday.

ANC Youth League president Julius Malema has faced widespread criticism for singing the song at his birthday celebration in Polokwane last week and at a student gathering in Johannesburg on Tuesday.

In her weekly newsletter, Zille said she had written to Zuma, pointing out that hate speech was unconstitutional and asking him what he intended to do about it.

"I have said that his prevarication on Julius Malema suggests that he and the ANC endorse incitement to murder fellow South Africans," Zille wrote.

On Friday, Zuma refused to criticise Malema for singing the song. "I haven't said that he is right but I've said he has a right to raise issues," Zuma said.

"If we stop Malema you would say that apartheid has come back."

The 'new' apartheid

Zille said Zuma was facilitating "the new apartheid" by giving Malema free rein.

Her lawyers had written to Malema requiring him to withdraw his "latest hate-speech" by 17 March, to apologise for it and to undertake not to use hate-speech again.

"If he fails to do so we will interdict him in the Equality Court," Zille said.

She had high praise for former president Nelson Mandela, who stood for ethics and courage and who publicly rebuked former ANC Youth League leader Peter Mokaba for singing "kill the boer, kill the farmer".

"The ANC today makes us appreciate all the more the quality of Nelson Mandela's leadership, which stands as a beacon of ethics and courage.

"In 1993, when the firebrand former ANC Youth League Leader Peter Mokaba sang "kill the boer, kill the farmer" the ANC National Executive Committee, under Mandela's leadership, publicly rebuked him saying that the slogan undermined the policy of promoting racial reconciliation."