FW de Klerk, the Nobel peace laureate and former South African president, has warned that the country is again being poisoned by racism from political leaders, leaving Nelson Mandela's spirit of reconciliation "almost totally gone".

De Klerk suggested that the now retired Mandela must feel sad about the betrayal of the non-racial consensus he espoused as South Africa's first black president, and that only a "second reconciliation" could restore it.

"Since his retirement there's been an exponential moving away from the emphasis which he has put on inclusiveness and reconciliation and the exemplary example he has been to all of us with regard to reconciliation," de Klerk said in Johannesburg on Wednesday. "That spirit has faded and is almost totally gone."

Race is never far from the surface of South African discourse, whether in the form of a maverick youth leader singing Shoot the Boer – deemed inflammatory by white farmers – or black protesters marching on an art gallery over a depiction of the president's exposed genitals.

But de Klerk, the last apartheid-era president, accused the current generation of African National Congress (ANC) leaders of cynically manipulating sensitivities for political ends.

He cited president Jacob Zuma, who told an ANC policy conference last month: "The economic power relations of the apartheid era have in the main remained intact. The ownership of the economy is still primarily in the hands of white males as it has always been."

De Klerk said: "The best example is the president publicly saying that the biggest stumbling towards black advancement are white men. Just read his speeches and the speeches of other prominent ANC leaders and you will find the speeches absolutely regularly raising the issue of race and blaming all their managerial failures and mistakes on apartheid and the past.

"Racialism is called up, to my mind, in order to create a smokescreen behind which to hide the failure of good management and effective governance."

Asked where such rhetoric might lead, he replied: "It divides the country once again … we might need a second phase of reconciliation; I think we're already in need of it."

Mandela remains widely revered for saving the country from potential civil war when apartheid collapsed. But some in the ANC and outside it argue that political liberation did not deliver material change, and a "second transition" is required to achieve economic liberation from the white minority.

Asked how 94-year-old Mandela, with whom he shared the Nobel peace prize, would respond to a growing racialisation of politics, de Klerk said: "I can't speak for him. I would imagine that in as much as reconciliation has faded and in as much racism is again prevalent, he would be sad about it.

"I definitely blame elements in the ANC, not the ANC per se. I think there are moderate people in the ANC who in all probability also share deep concerns about new tendencies but who might feel themselves marginalised or intimidated. I don't want to take it further."

A World Bank report this week confirmed that South Africa is one of the most unequal societies in the world: the top 10% of the population account for 58% of the country's income, while the bottom 10% account for 0.5%. Poverty remains a race issue, despite a growing black middle class. Trade unions say 74% of black people of working age are unemployed, compared with 35% of whites, and estimate that fewer than 5% of companies listed on the Johannesburg stock exchange are black-owned.

But de Klerk insisted: "The black share of the economy in South Africa has grown exponentially and fairly dramatically even before 1990, but specifically also since 1994."

Speaking earlier at a conference organised by his foundation, the former president insisted that race was being used as an excuse to deflect criticism. "Unfortunately, the Mandela and [Thabo] Mbeki era of national reconciliation is over," he told delegates. "Much of the proposed 'second phase' of the national democratic revolution is openly directed against white males – who are quite unjustly blamed for the triple crisis of continuing unemployment, inequality and poverty. This happens at a time when government at the highest level exacerbates racial tensions by using aggressive racial rhetoric, by supporting the singing of racially provocative songs and by condoning the incendiary racial threats of some of its formations."

One man frequently cited as a source of racial tension is Julius Malema, who was expelled earlier this year as president of the ANC youth league. But he denies that he is the personification of white fears.

"If they are scared, that is their own problem, they are cowards," Malema, who remains politically active, told the Guardian. "They can't fear democratic debate. They've never seen me attacking or killing white people … in me they've got nothing to fear. I am their defender. I've got their interests at heart."

He added: "The day we resolve the problems is when we resolve the problems of those people in Alexandra township [in Johannesburg]. That's the day they will no longer live in fear. They live in fear not because of me but because they know they are surrounded by a majority of poor people who can wake up one day, get into their kitchens and grab everything that they have. Hence the big walls, because they know what they are doing is an injustice. Their conscience is speaking to them. It's not about Julius."