A senior Midvaal municipality official is facing a disciplinary hearing for allegedly calling protesters "k*****s", the municipality said on Wednesday.
It said this apparently happened during a strike last year.
A complaint was lodged against Hendrik Brits and he was immediately suspended pending a disciplinary hearing, Midvaal municipal manager Albert de Klerk said.
The disciplinary hearing would continue on Thursday.
De Klerk said any Midvaal municipal official found guilty of racism would immediately be fired.
The SA Municipal Workers' Union in Midvaal said it would protest outside the municipal offices in support of its members, who were testifying.
The union lodged a complaint with the municipality in August last year, when Brits allegedly used the offensive word.