Security at the University of the Free State in Bloemfontein, where the ANC was holding its national conference, had been beefed-up on Saturday.
Media were scheduled to have a meeting with organisers on Saturday morning but on arrival they were refused entrance onto the campus.
Reporters had to park their cars outside campus and walk.
All entrances to the university were guarded by police officers.
Police at the entrances said cars needed to be searched and checked at the Tempe Military Base. Each vehicle would then receive a clearance sticker which would allow them access to the campus.
Service providers and ambulances were also turned away because they did not have clearance stickers.
The African National Congress's national conference starts on Sunday. - Sapa