Oscar Pistorius mental condition claim is "a fallback position," claimed prosecutor Gerrie Nel
Oscar Pistorius is engaged in 'self harming behaviour' because he is lonely and isolated, according to his uncle. Getty

A close relative of Oscar Pistorius has voiced concern he is engaging in 'self-harming behaviour' caused by his trial ordeal and killing Reeva Steenkamp.

Uncle Leo Pistorius said he was worried about the fallen star was tormented by "loneliness and isolation" and said he feared such feelings would only get worse for him.

His words came after Pistorius was involved in a nightclub brawl during which he was pushed over by a man named Jared Mortimer, last weekend.

Pistorius' camp claimed Mortimer aggressively confronted the paralympian about Steenkamp's death. Mortimer claims Pistorius ranted at him about his power and insulted South African president Jacob Zuma.

Admitting he thought Pistorius, 27, was "unwise" to have visited the VIP club in Johannesburg while the judge in his trial is reaching a verdict, Leo said the runner was getting helping help from his family.

In a statement he said: "Those of us closest to him have been witness to his escalating sense of loneliness and alienation. This, we believe, is underlying some of his self-harming behavior.

"As a family we are counselling Oscar to find ways of dealing with his feelings of isolation."

Pistorius was said to be at risk of developing mental health problems by defence lawyer Barry Roux, who cited Steenkamp's death and Pistorius' trial as reasons.

Fortunately for Pistorius, his nightbrawl brawl shall not count against him in the trial, with South Africa's National Prosecuting Authority saying he did not breach his bail conditions by going there.

The murder trial has adjourned for one month while judge Thokozile Masipa considers her verdict. South Africa does not have jury trials.