Startled players from both sides tried to separate the two and McHugh dislocated his shoulder in the ensuing fracas.
"What happened was unacceptable," said Oberholzer at a hastily arranged press conference at the stadium.
Van Zyl, who owns a mining supply company, was detained by KwaZulu-Natal police. The father of three, played rugby when he was younger. "The whole of the stadium was angry with the referee. It's just that I decided to do something about it," van Zyl told the South African Sunday Times from the back of a police van.
"Referees around the world think they are bigger than the game and they're not. Fans like me is what rugby is about."
van Zyl was freed on bail of 3000 rand ($667) after appearing in the Durban Magistrate's Court where he was charged with assault, grievous bodily harm and trespass. He will appear again on September 9. Asked about the incident following his appearance he told the Herald: "Of course I regret it."