A culture of corruption and impunity is seeping through every level of government and corroding society, Agang leader Mamphela Ramphele said.

"It is estimated that corruption robs us of more than R30 billion of the government's budget every year through an abusive procurement system," she said in Johannesburg.

"The most outrageous example is in the private palace costing more than R200 million which was built for President [Jacob] Zuma at Nkandla."

Ramphele listed other examples, such as irregular leasing for police buildings, and civil servants and their families doing business with government.

She said it was no wonder that the Eastern Cape health department had "collapsed" after government acknowledged that 8000 public servants in the province were doing business with the department.

"These are not just bumps on the road to a better future. These are not the inevitable pains of a transitional period," Ramphele said.

"They are a betrayal of the founding principles of our democracy, a betrayal of what our brothers and sisters, our fathers and mothers, who fought all those freedom fights and died."

Speaking at the Wits Origin Centre, she told students, media, and business people that the fight against apartheid had not been fought so that millions of South Africans could live like the "forgotten people".

It was important for South Africans to overcome their "fear" and stand up against corruption and patronage.

Quoting former president Nelson Mandela, she said "never, never, never again" should the oppression of one by another in South Africa be allowed.

"Let us mark a formidable war on corruption," Ramphele said.

"We can't govern a 21st century democracy without knowledge, science, and technology... Our [Agang's] policies are going to be based on evidence."