The J-Bay Open surf event in South Africa has been suspended after a top Australian surfer was attacked by a shark.

The incident, captured live during coverage, involved 34-year-old Mick Fanning as he was about to compete against fellow Australian Julian Wilson.

The dramatic footage shows a shark approach Fanning as he sets up to begin his heat, and appears to knock the surfer completely off his board as both thrash in the water.

Miraculously, Fanning wasn't injured, but he was a bit shocked when he spoke to reporters, noting his leg rope was eaten and that he punched the shark in the back during the encounter.

"I was just sitting there and I felt something just get stuck in my leg rope, and I was kicking trying to get it away," Fanning told Sky News.

"I just saw fins. I was waiting for the teeth."

Organizers told the Australian Broadcasting Company two sharks were spotted in the area.