South African police said in the late afternoon they did not know where Mrs Mugabe was.
A 20-year-old South African woman has accused Mrs Mugabe of hitting her on the head with an extension cord during a confrontation at a hotel.
She released an image of a face injury online. Mrs Mugabe has not commented.
Gabriella Engels accused Mrs Mugabe, 52, of hitting her after finding her with her two sons in a hotel room in Sandton, a plush suburb north of Johannesburg, the BBC's Pumza Fihlani reports.
The attack is said to have happened on Sunday evening.
