A total of R24 million or about US$2m was stolen from a plane at OR Tambo International Airport on Tuesday evening, News24 reported.
Its spokesperson Hangwani Mulaudzi said there was a high level investigation into the robbery. He declined to give out further information at this stage.
After SAA flight 294 landed, people in a marked police vehicle intercepted the money.
A white Mercedes-Benz is believed to have been used in the operation.
Airports Company South Africa spokesperson Trevor Jones said there had been a robbery, but he could not confirm the amount of money stolen.