A spokeswoman for Oscar Pistorius on Tuesday said suggestions that the Paralympian had taken acting lessons ahead of his emotional murder trial testimony were "totally devoid of any truth.”

We "deny that our client has undergone any 'acting lessons' or any form of emotional coaching,” Anneliese Burgess, media manager for the Pistorius family, said in a statement on his website.

Pistorius broke down repeatedly in the witness box as he gave his version of shooting dead girlfriend Reeva Steenkamp on Valentine's Day last year.

His vomiting and loud crying have often disrupted proceedings, and some have questioned his sincerity.

Well-known South African columnist Jani Allan claimed he had been coached for his emotional performance.

"I have it from a reliable source that you are taking acting lessons for your days in court. Your coach has an impossible task," she wrote in an open letter posted on her website on Monday last week.

"Oscar, you are the latest in a long line of faux heroes. Like so many who preceded you, you have betrayed your people and disappointed your fans," she added.

But the Pistorius family described her allegations as "fictitious", saying any "suggestion that Mr Pistorius 'took acting classes' is totally devoid of any truth".

"This type of comment makes a mockery of the enormous human tragedy involving the Steenkamp family and our client and his family," Burgess said in the statement.

Pistorius says he fired four shots through a locked cubicle door thinking Steenkamp, a 29-year-old model, was an intruder coming to attack him in the dead of night.

Prosecutors have argued that the shooting came after a row in the early morning hours.

His trial was postponed for the Easter break and will restart on May 5. (AFP)