AfriForum says the Zimbabwe High Commission does not have the legal authority to join the matter at this stage.
Civil rights organisation, Afriforum is today approaching the High Court in Pretoria to review the diplomatic immunity granted to Zimbabwe's first lady Grace Mugabe.
This came after Mugabe allegedly assaulted 20-year-old model Gabriella Engels at a Sandton Hotel on August 13.
Mugabe was allowed to fly out of country under the cover of darkness after Nkoana-Mashabane had granted her immunity from prosecution. In doing it this way, it could be assured that she did receive the notice, he said.
Public outcry over this case has seen political parties such as the Democratic Alliance questioning the issue of diplomatic immunity.
Debbie and her daughter Gabriela Engels at the Pretoria High Court appear for an interlocutory application seeking permission to serve papers to Grace Mugabe in Zimbabwe. On August 25 the DA took the matter directly to the Constitutional Court where they filed papers to request "direct access" to argue against the decision by the minister and that it "should be set aside as wholly without legal merit and should thus be declared unconstitutional and invalid".
On September 6, MP Stevens Mokgalapa, DA spokesperson on global relations and cooperation said that Mashabane had refused to appear before Parliament to account for her role.
The court has given AfriForum until 11 October to submit further reasons why the High Commission may not intervene.
Judgment has been reserved.