A memorandum was submitted to Groblersdal police station on Tuesday after the recent murder of Johan Myburgh, 33, on his parent's farm outside the town on April 19.
Kallie Kriel, chief executive of AfriForum, an independent, non-profit organisation, said: "Those who inflame hate and aggression towards farmers have to be regarded as accomplices to the murders of farmers."
Kriel, who signed the memorandum, said theft could not be used as a motive for farm murders, as it was not necessary to torture and murder people when robbing them.
Kriel urged police to launch a comprehensive investigation into the role played by hate speech by politicians against farmers.
He accused Agriculture Minister Lulu Xingwana and her deputy, Dirk du Toit, of being party to inciting hatred against farmers.
Accused of ethnic genocide
"The minister, for example, made herself guilty of hate speech on December 5 2006 during a gathering at Church Square, Pretoria, by falsely alleging that the agricultural industry was riddled with cases of violence against women and children and that farmers raped and assaulted farm workers," he said.
He said Du Toit even went so far as to accuse farmers of committing ethnic genocide.
He said that during the ANC's protest action at the first court appearance of 18-year-old Skierlik murder suspect Johan Nel, ANC MP Patrick Chauke publicly blamed the white community for the murders, after which protestors yelled slogans such as "Kill the Boer, kill the farmer!".
Nel, who is not a farmer, is accused of killing four people, including a three-month-old baby, and wounding six in a shooting rampage at Skierlik informal settlement near Swartruggens in North West in January.
Kriel said posters with slogans such as "One settler, one bullet!", "Kill the Boer, kill the farmer!" and "Maak dood die wit man", were also displayed during the court appearances.
No arrest in Myburgh murder
At the funeral, speaker after speaker launched scathing attacks against the farming community and whites, and called for "action" against farmers.
Groblersdal police station's Inspector Nopofu Jelle said the community's concerns would be taken up by the provincial police commissioner's office.
Meanwhile, no one has been arrested yet for Myburgh's murder.
"They shot him in the back of his head through a window," said resident Yolanda Duvenage on Tuesday.
She said police had a responsibility to ensure the safety of farmers.