"Members of the South African Police Service in Limpopo are fully prepared and ready to ensure that the president's lecture is conducted in a peaceful and orderly environment," provincial commissioner Lt-Gen Simon Mpembe said.

Zuma was expected to deliver a memorial lecture on the legacy of former ANC president Nelson Mandela, amid tight security over fears he might be heckled by supporters of axed youth league leader Julius Malema.

The lecture was scheduled to start at 3pm at the Holy Worship Church in Shiyandima.

"Various police units ranging from air wing (air support), public order police, operation response service, K9 (dog unit), bomb disposal unit, crime prevention, to detectives, have been deployed to ensure that security is not compromised," Mpembe said.

He warned that police would not tolerate any act that could compromise safety and security, and would take drastic steps to restore order. Firearms and knives would not be allowed into the venue.