A woman has been arrested after a Whatsapp voice message circulated on social media seeming to call for black people to be banned in South Africa, police said. A case has been opened in Boksburg, a suburb 30 kilometres (18 miles) east of Johannesburg, against a woman who allegedly sent the voice message calling for a ban on black people instead of pitbulls. Police said in a statement Saturday they were investigating “a case of crimen injuria”, or wilful injury to a person’s dignity by the use of racially offensive language. “The suspect aged 60 years old was arrested and released the same day on a warning”. She will appear in court next March. The voice message follows a call from some South Africans to ban pitbulls following a rise in cases reported where the dogs have mauled people, particularly children. Gauteng Premier Panyaza Lesufi on Twitter thanked police for their “swiftness”, adding, “racists are mindless and useless!”.