South Africa's president is vowing to purge his party of "bad and deviant tendencies" as he prepares to appoint a new Cabinet following a victory in national elections.

The 57% share of the vote was the worst-ever election showing for the African National Congress, which has ruled since the apartheid system of racial discrimination ended 25 years ago.

Low voter turnout also reflected the frustration of many South Africans after corruption scandals around the ANC that led former president Jacob Zuma to resign last year under party pressure.

Current President Cyril Ramaphosa in his first speech to supporters since the election win said Sunday he will not appoint leaders who work "to fill their own pockets."

Ramaphosa is believed to be facing a revolt within the party by Zuma allies.