Images of the bloody bathroom where Oscar Pistorius shot his model girlfriend in February have been leaked to Sky News, just days before the South African paralympian sprinter appears in court charged with the murder.

The pictures, shown on the British news channel, show a bathroom, with blood on the toilet seat and a door with two marked bullet holes.

There was also a pool of blood on the floor next to the toilet seat. The two bullet holes are located just below the door handle.

The 26-year-old athlete claims that he shot his lover, Reeva Steenkamp, through a locked bathroom door after mistaking her for an intruder.

Lawyers for the double amputee known as "Blade Runner" have written to the country's prosecution authority to complain about the leaked pictures.

"I can confirm that I have written to the National Prosecution Authority PA," attorney Brian Webber told AFP, refusing to give details.

Sky News has not revealed how it got hold of the graphic images, the first to emerge of the crime scene.

Police said they were unaware of the source of the leaked photographs.

"The origin of the photos in question is not known," police spokesman Phuti Setati said, adding that the leak would not jeopardise the case.

"Our investigations into the matter are on track and our goal is to secure conviction," he told AFP.

The position of the bullet holes in the images appears to back Pistorius's claim that he fired the shots while standing on his leg stumps.

He said he used a cricket bat to force open the door after realising his mistake. He then carried the 29-year-old model downstairs to try and resuscitate her.

Police say Steenkamp was shot three times, with wounds to her head, elbow and hip.

The shooting happened in the early hours of Valentine's Day inside the athlete's home in an exclusive high security housing complex outside the capital Pretoria.

Sky News also showed an image of a wrapped-up Valentine's Day gift Steenkamp was planning to give to Pistorius.

The couple had been dating for several months before the fatal incident.

Pistorius is facing a charge of premeditated murder and is currently out on bail.

His arrest shocked the world and gripped South Africa, where he was considered a national hero for being the first double amputee to compete in the Olympics last year.

Pistorius is set to make his next court appearance on Tuesday in what will likely be a brief hearing. A trial is expected by the end of the year. If found guilty, he faces a life sentence.

During the athlete's bail hearing in February, the lead investigator was forced to admit multiple police errors in the case, undermining earlier claims that witnesses had heard arguing and a woman screaming before shots were fired.

The detective admitted that protective shoe covers were not used at the crime scene and that one bullet at the site had been overlooked, only to be discovered later by the defence's forensic team. It then emerged that the lead detective was himself facing charges of attempted murder for shooting at a mini bus in 2011.