South African President Cyril Ramaphosa vowed on Wednesday to act against those responsible for state capture.

"We have taken significant measures to end the scourge of corruption, which steals from the poor and enriches a few," Ramaphosa said at an event marking the Jewish New Year, Rosh Hashanah, in Cape Town.

He was speaking as the Judicial Commission of Inquiry into state capture was conducting public hearings with testimony of a number of former senior government officials. Former president Jacob Zuma and his son Duduzane Zuma are also expected to testify before the commission.

The two men allegedly are embroiled in state capture which refers to collaboration with the wealthy Indian Gupta family in looting from the state coffers through the awarding of lucrative contracts with state-owned enterprises to the Guptas. Zuma is also accused of being influenced by the Guptas in the appointment of cabinet ministers when he was in power.

The State Capture Commission is the spearhead of a range of interventions which include Special Investigating Unit probes and other inquiries to help South Africans understand the depth of criminality that has impoverished the society and economy, Ramaphosa said.

"We must pledge as a nation that we will never allow our ethical and economic fibre to be undermined on this scale again, or on any scale for that matter," said Ramaphosa.

South Africans, he said, must build a nation based on sound values, inspired by honest leadership.

Also on Wednesday, Zuma said state capture doesn't exist and that the term is not being used correctly.

None of the legislature, the judiciary and the executive, which form the state, are captured, Zuma said while addressing students at the Walter Sisulu University of Technology in Mthatha, Eastern Cape Province.

Zuma said the term of state capture was used by people who wanted to achieve certain political outcomes.