South Africa's Paralympian sprint star Oscar Pistorius will go on trial in March charged with murdering his girlfriend on Valentine's Day, a magistrate ruled at a packed court hearing on Monday.

The 26-year-old double amputee, who looked subdued as he arrived in court in the capital Pretoria, faces a life sentence if found guilty.

Pistorius was back in the dock six months after shooting dead Reeva Steenkamp in the bathroom of his upmarket Pretoria home in the early hours of February 14.

The athlete known as "Blade Runner", who is currently out on bail, has admitted killing her but denied murder, saying he shot Steenkamp through a locked bathroom door because he believed she was an intruder.

Magistrate Desmond Nair said the trial would start at the High Court on March 3 and run until March 20.

Monday's court hearing coincided with what would have been the 30th birthday of Steenkamp, a blonde cover girl and law graduate, who died with gunshot wounds to the head, elbow and hip.

Pistorius walked into the Pretoria court wearing a black suit and light blue shirt, and started praying with his sister Aimee and brother Carl, holding hands with them and crying.

Local media had said he may also be charged with gun offences as the state tries to cast him as aggressive and trigger-happy, however, no other charges were listed on the indictment.

Pistorius allegedly fired a gun through the sunroof of an ex-girlfriend's car, and earlier this year reportedly discharged a gun by accident at a Johannesburg restaurant.

Monday's hearing was brief, as lawyers had already agreed to start the trial next year amid backlogs in the South African courts.

A single senior judge will hear the case as South Africa does not have a jury system.

Pistorius broke down several times in court during his February bail hearing and family members have spoken openly about his trauma.

Key aspects of the police investigation into Steenkamp's death came under scrutiny during the lengthy bail hearing.

Ballistics reports from the bathroom door suggest Pistorius was on his stumps when the shooting took place, South Africa's Sunday Times reported.

The athlete, who earned his nickname the "Blade Runner" for the fibreglass prosthetic legs he uses in competition, was born without calf bones and had both legs amputated below the knee when he was 11 months old.

Prosecutors have said he donned his two prostheses before firing four shots through the door, a delay they thought would prove the murder was planned.

Paralympic champion Pistorius catapulted to fame at last year's London Olympics as the first double-amputee to compete against able-bodied athletes.

But the killing sent shock waves around the world and since then his reckless past and love of fast cars, beautiful women and guns has emerged in media reports.

The case halted his participation in athletic events and ended lucrative endorsement deals with US sportswear giant Nike and French cosmetic firm Clarins.

Now South Africa's much-maligned police force is under immense pressure to help secure a conviction, after the bail hearing showed up shoddy police work that led to the whole investigation team being replaced.

Police failed to find all the bullets fired, potentially contaminated the crime scene and misjudged the distance to the house from which a witness claimed to have heard shouting earlier in the night.

Pistorius was released on bail of one million rand ($99,000, 74,000 euros) a week after killing Steenkamp.

Her parents, initially silent, later lashed out at him, speaking of quarrels their daughter had with the athlete in their five-month relationship.