JOHANNESBURG - A video of a motorist travelling at alarming speeds on a public road has surfaced on social media.

The vehicle clocked 322km/h while travelling on the R21 in Johannesburg.

It appeared that the unidentified motorist was speeding on the highway, clocking 240km/h before slowing down slightly, only to pick up speed again when he saw a motorbike.

A voice on the video is heard saying in Afrikaans, "laat hom gaan, laat hom gaan, dan gaan haal jy hom" (let him go, let him go, then go after him).

As the motorbike overtook the speeding car, the passenger filmed the speedometer, which showed the car driving at over 320km/h.

The passengers are heard laughing, saying that the biker was in a hurry.