Oscar Pistorius has been accused of "tailoring his evidence" at his murder trial, where he denies murdering his girlfriend Reeva Steenkamp.

Prosecutor Gerrie Nel repeatedly challenged the Paralympian's account of events while questioning him about whether the alarm in his home was activated on the night he shot Ms Steenkamp.

The confrontation led Pistorius to admit he could be giving inconsistent answers because he was tired - prompting the judge and prosecution to ask if he was able to continue with his evidence.

Mr. Nel also claimed the athlete was lying about an incident when he claims he was shot at while driving on a highway in 2008 or 2009, because he could not remember who he had called for help that night.

He said "It is so improbable that you can not remember - the only reason you can not remember is that it didn't happen".

The athlete was asked about security measures at his house, as the lawyer - known as the "Pit Bull" - sought to undermine his claims that he was concerned about crime.

Pistorius told the court he had never been a victim of crime at his Silver Woods home, apart from an occasion when he said police stole his watches.

He said security measures in the area had been upgraded several times, but he had never attended meetings of a home owners association where those issues were raised.

Judge reprimands prosecution

Mr. Nel again suggested the athlete was a selfish person, raising his previous statements that Ms Steenkamp had often prayed for him and his training.

At one point, the barrister's combative approach earned him a reprimand from Judge Thokozile Masipa, who warned him, "mind your language" after he called Pistorius a liar.

Mr. Nel has sought to dismantle the Paralympian's heroic life story and portray him as self-centred, short-tempered, gun-obsessed and eager to shirk responsibility for his actions.

This morning Mr. Nel has been asking about his and Reeva's faith.

Speaking outside court, reporter Martin Brunt said "He clearly wants to put him under enough pressure to admit what the prosecution say really happened that night - that Pistorius woke up, they had an argument, she ran away to the bathroom screaming and he chased her and shot her dead".

Pistorius denies premeditated murder and illegally possessing ammunition in relation to Ms Steenkamp's death. He also denies two further counts related to shooting a gun in public in separate incidents prior to the killing.