England-based Springbok Brian Mujati has accused fellow Bok Heinke van der Merwe and another South African, Steven Sykes, of making racist remarks towards him.

The incidents, which reportedly took place in a pre-season match between Ireland province Leinster - for whom the two South Africans, Van der Merwe (a one-Test Bok) and Sykes play - and Mujati's English club Northampton Saints, in Dublin, Ireland, on Friday.

Leinster said they will hold an internal investigation.

"Steven Sykes and Heinke van der Merwe were calling me a baboon during the scrums last night," Mujati posted on his Twitter feed on Saturday.

"Racism is still alive and things don't change."

"I was shocked by how blatant they were being and to think I actually thought I knew Heinke from back in the Lions days," Mujati posted on the social network.

"The guy then tries to shake my hand after the game. Naturally I kindly told him to f*** off.

"I wish them all the best with their careers."

Leinster Rugby said in a statement that there would be a full internal investigation into the matter.

"The management of both teams are in close communication and hopefully the matter will be resolved as soon as possible," it said.

The Zimbabwean-born Mujati has earned 12 caps for the Springboks, while Van der Merwe has one national cap to his name and Sykes has featured for the Emerging Boks.

In the last eight months, the big prop forward has gained a tremendous support base at his club with cries of "Mooooooooj!" often emanating from the stands when he touches the ball.

Since joining Saints, Mujati has established himself as one of the best tightheads in world rugby, but issues revolving around his passport took him out the running as a real contender for the World Cup squad.