Grace Mugabe is alleged to have assaulted South African model Gabriella Engels in Johannesburg in 2017 but was granted diplomatic immunity to leave the country.
The High Court in Gauteng, however, last year ruled that the decision by International Relations Minister Maite Nkoana-Mashabane to grant Mugabe diplomatic immunity should be set aside.
Afrikaaner rights group, Afriforum, which is representing Engels, today said the NPA had applied to have Grace Mugabe extradited but the NPA refused to comment on the matter.
Afriforum says it will apply for private prosecution if the NPA refuses to prosecute Grace Mugabe.
Zimbabwe President Emmerson Mnangagwa said at the weekend that former President Robert Mugabe was in Singapore receiving treatment.
Mugabe turned 95 in February.
Grace Mugabe, 41 years younger than her husband, has also been facing health problems.