A South African former police officer has told a court that government leaders during the apartheid era encouraged him to carry out attacks on black activists.

The former officer, Eugene de Kock, was giving evidence in the trial of the former President, PW Botha, who's charged with contempt for refusing to appear before the Truth and Reconciliation Commission.

Mr de Kock is currently in jail for his role in the murder of government opponents.

He told the court that he and other former members of the security forces had been betrayed by politicians who'd encouraged the attacks at the time and later denied knowledge of them.