South Africa's last white president took a swipe at the ruling African National Congress (ANC) on Friday, saying it discriminated against people based on race.

"We were never consulted about the ANC's approach to transformation and we do not accept it," FW de Klerk said in a speech to mark 20 years of democracy in Cape Town.

"These policies – in the ANC's so-called second phase of transition – are overtly directed against South African citizens on the basis of their race. That is unconstitutional and the antithesis of the goal of national reconciliation."

De Klerk, who unbanned the ANC and released South Africa's first black president Nelson Mandela from 27 years in prison in 1990, said South Africa had failed to provide decent education and jobs for its people.

The time had come for "serious talks" between the government and "all those who are targeted by its version of transformation", such as farmers, the media, civil society organisations, and small and large businesses.

"We have failed to provide all but a small percentage of our children with decent education," he said.

De Klerk, who shared the Nobel peace prize with Mandela in 1993, said South Africa's "greatest" transformation failure was that it was now a more unequal society than it was in 1994.

He referred to the country's Gini coefficient or measure of income inequality.

"Our Gini coefficient of 0.7 makes us one of the most unequal societies in the world."

The closer the coefficient is to one, the higher the inequality in a country.

"Not only has inequality increased throughout society, it has also increased within each of our population groups.

"Clearly, the government's policies to promote equality have failed.

"The main beneficiaries of affirmative action and black economic empowerment have been the emerging black middle class and elite – and not the vast majority of truly disadvantaged South Africans."

He said, however, that the ANC had achieved remarkable successes since it came to power under Mandela in 1994, including building three and a half million new homes, providing electricity, water and sanitation to 80% of the population and extending social grants to more than 16-million people.