South African rugby officials are offering a reward to help find three men responsible for a racist attack on a black woman at the Wallabies v Springboks Test in Johannesburg on Saturday.

South African Rugby Union president Oregan Hoskins has expressed outrage at the attack and alarm that it was witnessed by others who didn't intervene.

Hoskins said the SARU was pursuing all avenues to find the men who racially abused and assaulted the female Springbok fan in the corridors at Ellis Park at halftime in the Tri Nations match, won 53-8 by South Africa.

"This was a despicable action by three men whom every Springbok on the field that day would have roundly condemned," said Hoskins.

"But what's as alarming is that other supporters passed by without intervening."

"Rugby is committed to rooting out this kind of behaviour and every time even an isolated incident rears its ugly head we shall come down hard on the perpetrators when we can identify them."

Host province Golden Lions and SARU staff contacted the victim to offer their apologies and express their sympathy as well as attempt to identify the individuals responsible.

"They will have friends and acquaintances who saw what happened and we urge them to contact our offices so that we can take action," said Hoskins.

"If they need any encouragement there is a R10,000 ($A1500) reward on offer.

"We will also be contacting all 14 of our provinces to underline that we have zero tolerance for this kind of behaviour anyone found guilty of such actions will be banned from our stadia.

As a result of the incident the Golden Lions are investigating placing anti-racism stickers on stadium seats.

The sticker will contain information about an SMS number supporters can use to immediately identify racist incidents. AAP