There are 26 confirmed coronavirus cases at the East London Correctional Centre in Westbank.
A total of 23 cases are officials working at the centre, while three are inmates.
All three of the infected inmates are women.
Deputy minister of justice and correctional services Phathekile Holomisa, says authorities are still awaiting the test results of other inmates.
“We’re still waiting for the results of others but there are some who have tested negative. There are 269 offenders here…”
The Department of Correctional Services launched mass covid-19 screening at the facility last week, after a second female official tested positive for a coronavirus infection.