Mahlangu was at the Mabopane police station, and would be taken to Hartbeesfontein correctional facility, said National Prosecuting Authority (NPA) spokesman Mthunzi Mhaga.
Earlier, Judge Julius Matojane of the High Court in Pretoria set aside 28-year-old Mahlangu's bail, saying the magistrate in Ventersdorp had made "incomprehensive findings" in his awarding of bail.
"The bail application is set aside and a warrant of arrest must be issued immediately," said Matojane.
In his ruling, Judge Matojane said Mahlangu could be a flight risk, even though he had met his bail conditions.
The verdict brought a sigh of relief from AWB members clad in their khaki uniforms in the court room.
Matojane said Mahlangu had given false information during his bail application and that magistrate Magaola Foso should have found this a mitigating factor in the granting of bail.
Although Mahlangu said he was originally from Bela-Bela in Limpopo, a home affairs official told the Ventersdorp Magistrate's Court during the bail application that Mahlangu's name was not on the South African population register.
