The Association for Rural Advancement (Afra) has lambasted the police for appearing to be more sympathetic to white farmers than to blacks.
This comes after a high-profile police unit was deployed at a Melmoth farm in northern KwaZulu-Natal after a farm manager was murdered by a mob last Tuesday.
Kenneth Lionel Eva, 49, was clubbed to death by the mob in a dispute over land.
The police said they deployed the extra officers because they feared more attacks.
Afra spokesman Sifiso Kunene said the quick reaction of the police showed that police "value a white person's life more than that of a black person".
"We do not condone any killings, but we note with great concern the reaction by the police whenever a white farmer is killed or attacked," he said.
"They move swiftly and in most cases action is taken, which is not the case when a black farmer or worker is murdered.
"We wish they acted the same. This country would then be the greatest place to be," Kunene said.
Deputy police commissioner Bala Naidoo denied Kunene's allegations.
He said the police investigated all crimes reported to them and made arrests when they were justified by evidence.
"The police were deployed in Melmoth because tensions existed after the killing of the farm manager," Naidoo said.
Kunene said there had been a number of instances of the police failing farm workers or farm dwellers.
"When Solomon Mbuyisa, of Pongola, Irene Masikane, of Howick, and two children in Eshowe were killed by white farmers, no arrests were made.
"The cases were dropped for no apparent reason," Kunene said.
Mbuyisa died after a farmer allegedly dragged him behind his van.
Masikane died after a farmer allegedly drove over her several times.
Two children, aged 12, died after farmers allegedly shot them for stealing sugar cane.
One died on the scene and the other died a month later in the intensive care unit of a local hospital.
Kunene said Afra would arrange a meeting with the province's MEC for community safety and liaison, Bheki Cele, to discuss how these and other cases could be resolved.