A South African woman who hurled racist abuse at a black police officer in a clip that went viral has been sentenced to three years in prison with one year suspended.

Vicki Momberg was found guilty in November on four counts of crimen injuria, or the willful injuring of someone's dignity.

It's the first time a South African has received prison time for the offense.

"We've had crimen injuria (cases before), but they have always been coupled by other charges. This is the first for a prison sentence for crimen injuria on its own," National Prosecuting Authority spokeswoman Phindi Mjonondwane said.

Mjonondwane said the court's punishment sets a precedent for future cases: "We are pleased with the sentence. This sends a clear message to those who undermine other people's rights."

Momberg, a former estate agent, was caught on video berating South African Police Service officers who had stopped to assist her after thieves broke into her car in Johannesburg. She repeatedly used a highly offensive slur that was commonly used to insult and demean black people during apartheid.

Magistrate Pravina Rugoonandan denied Momberg bail after the sentencing in Johannesburg. Momberg's lawyers are expected to lodge an appeal next week.

Minister of Justice and Correctional Services Michael Masutha welcomed the sentenced and reiterated his department's commitment to fighting racially motivated crimes.

"We believe that this strong sentence will deter would-be hate crime perpetrators in our society. We also find it defeating and disappointing that we are dealing with a case of this nature in a year where we celebrate the year of Nelson Rolihlahla Mandela," Masutha said.

The prison sentence brings a clear warning that race-based abuse for which Momberg was found guilty "will not be tolerated", the Nelson Mandela Foundation said Wednesday in a statement.

It was not enough to act against "incidents" of racism, and underlying privileges that cause racism in post-apartheid South Africa must be addressed, the non-profit organization added.

Momberg's sentence is significant for its severity, but not for the act itself.

In 2016, a real estate agent, Penny Sparrow, was ordered to pay around $10,000 to charity after she was convicted of hate speech for a Facebook post in which she referred to blacks as "monkeys."