The mental health of Oscar Pistorius is firmly in the spotlight as his murder trial resumes today after a lengthy break.

The fallen track star has completed six weeks of mental health tests at a psychiatric hospital in Pretoria.

A team of four mental health experts are set to deliver their findings to the court at which Pistorius, 27, is standing trial for killing his girlfriend Reeva Steenkamp.

Judge Thokolize Maispa ordered the disabled runner to undergo the tests at the request of the prosecution, after a defence witness claimed Pistorius had Generalised Anxiety Disorder (GAD).

If the experts are convinced Pistorius has the disorder, the judge may rule he was not in control of his actions when he blasted Steenkamp three times on Valentine's Day last year. Much of Pistorius's defence pivots upon the claim that he lived in a constant and extreme fear of crime.

The high profile trial has badly overrun the three weeks it was initially expected to take when proceedings began in March.

Last week, one of the four experts who assessed Pistorius suffered a heart attack.

Pistorius denies murdering Steenkamp and claims he thought burglars had broken in to his luxury home on the outskirts of Pretoria. The prosecution claim he shot her dead in a fit of rage following an argument.