Remorseful Waratahs lock Justin Harrison said he would wear any suspension or fine meted out after admitting to racially vilifying a black South African rugby player.

The towering second rower owned up to making a racial slur directed towards Cats winger Chumani Booi in last weekend's Super 12 match in Johannesburg after initial reports had indicated Harrison's teammate Nathan Grey had made the comments.

Grey strenuously denied the allegations on Wednesday morning, saying in a statement he had heard the remarks during the match and was personally appalled.

After hearing of the reports Harrison contacted Waratahs team management, admitting the comments were made by him.

"Having had the benefit of hindsight now and indeed immediately when the situation did occur on the field, it's something I am incredibly remorseful over and will regret for the rest of my life," said Harrison.

"It was a very, very poor attempt to sledge a player on the sporting field - one which had racial overtones which is by no means indicative of my nature.

"I am extremely remorseful for what I've said and done and will do whatever it takes to make the situation right.

"I would understand any result that is given from a hearing process that will be no doubt undertaken."

The incident occurred during the early stages of the match on Sunday (AEDT) with Cats fullback Conrad Jantjes telling the Afrikaans daily newspaper Beeld what he believed Grey had said.

"Within the first five minutes, there was an up and under on Chumani. When he went to ground, I was part of the ruck and I heard Nathan say to Booi: 'Leave the ball you stinking black c**t'," the newspaper quoted Jantjes as saying.

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