The last leader of white South Africa launched an unprecedent attack on the conduct and policies of his successors in a speech that reflected deepening divisions in the so-called rainbow nation.
Mr de Klerk said there was no justification for Mr Zuma's outspoken acolyte Julius Malema, the ANC's Youth League president, to sing Shoot the Boer. Mr Malema calls the song "a legitimate struggle" anthem but is now facing a hate speech charge for singing it.
"The historical context is irrelevant," Mr de Klerk said. "It would be equally unacceptable for Afrikaners to sing Boer War songs calling on people to shoot the English - or for Americans to sing World War II songs about killing Japanese people."
He said Mr Malema's alleged claim that white farmers were "criminals" who stole land was also "unacceptable", and it was "even more" unacceptable for President Jacob Zuma to share a stage with him but not condemn his "racist" comments.
"Malema's behaviour is irreconcilable with the constitution that the president has sworn an oath to uphold," said Mr de Klerk.
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He warned South Africans that if they ignored such pronouncements, the consequences would be "dire".
Mr de Klerk also launched a wider assault on Mr Zuma's ANC, which is, he said, seeking to enforce black domination over the racial minorities and erode South Africa's liberal constitution.
He said cronyism, corruption and "divisive racial politics" were rife in government.
"I believe that we are approaching a pivotal point in our history where all South Africans of goodwill, regardless of their race, circumstances or political affiliation will have to rally around the constitutional rights, values and vision upon which our new non-racial democracy has been established," he said.
His outspoken intervention comes at a time of intense debate about race relations in post-apartheid South Africa.
Mr Malema's comments about whites stealing land has provoked fear among farmers of Zimbabwean-style land invasions. Mr Zuma did not contradict Mr Malema, though other officials said the remarks did not represent government policy.
Within the ANC, there have also been racial disputes. Jimmy Manyi, the government spokesman, inflamed tensions by criticising the "overconcentration" of coloured - the South African term for mixed race - people in the Western Cape.
His remark prompted Trevor Manuel, a powerful ANC minister, to condemn his colleague as "a racist in the mould of HF Verwoerd", the architect of apartheid.
Mr de Klerk said the ANC was seeking "massive and forced redistribution of property and wealth from the white minority to the black majority".
"Whites, Coloureds and Asians would be corralled into demographic pens in all aspects of their economic and professional lives according to the percentage of the population they represent," he warned.
"The prospects of South African citizens would once again be determined by the colour of their skins - and not by their skills, their contribution."
Dave Stewart, the executive director of Mr de Klerk's foundation said the ex-leader had taken a necessary risk in his speech. "It would be very easy when the going gets tough for Mr de Klerk to disappear off to Ibiza but he is an elder statesman and feels he has a duty to uphold the values he and Mr Mandela worked towards," he said.
Zizi Kodwa, spokesman for President Zuma, said Mr de Klerk had been misled by press headlines. He said: "Mr Zuma takes former president de Klerk very seriously but for him to just respond to headlines without checking the facts is very unfortunate."