The prosecutor in the Oscar Pistorius murder trial has accused the athlete of using emotional breakdowns under cross-examination to evade answering questions about the night he killed his girlfriend.

The Olympic and Paralympic sprinter says he shot Reeva Steenkamp in a tragic accident, firing at what he thought was an intruder hiding behind a locked toilet door.

Mr Pistorius faces life in prison if convicted of murder.

The athlete has broken down numerous times during the 22-day trial, including retching into a bucket.

He burst into tears again this morning when recounting the moment he screamed at what he thought was a burglar, prompting the judge to call a 30-minute adjournment.

"Get the f**k out of my house! Get the f**k out of my house!" a trembling Mr Pistorius said when asked to state precisely what he screamed at the perceived intruder.

He then burst into tears as family members in the public gallery rushed to comfort him.

Towards the end of the day, he again began to cry when answering questions about the immediate aftermath of the shooting.

State prosecutor Gerrie Nel said the athlete was just putting on an act to avoid having to answer his questions.

Mr Nel questioned why Mr Pistorius would get upset when being asked about whether he did or did not open doors leading from his bedroom to a balcony to shout for help minutes after the shooting.

"I cannot see how that can cause you to be emotional because you cannot remember how to open a door. We're not talking about Reeva," Mr Nel said, referring to previous breakdowns, which have usually been when he describes the shooting.

"You're not using your emotional state as an escape are you?" Mr Nel asked.

Mr Pistorius will likely remain on the stand for another few days.

The defence will then call up to 17 witnesses, including ballistics experts.

The double amputee gained world-wide fame for running on two fibre optic blades at the Paralympics and 2012 London Games. 

His legs were amputated below the knee shortly after he was born without calf bones.

The shooting on 14 February 2013 brought his career to an abrupt halt.

Originally set down for three weeks, the trial today entered its sixth week and has been extended until 16 May.