Oscar Pistorius
Pistorius is seen running on his stumps, his arm raised as if holding a gun.Seven Network / Sunday Night

Chilling footage has emerged showing Oscar Pistorius re-enacting the night he shot dead his girlfriend Reeva Steenkamp.

The leaked video, which was produced by an American company hired by the athlete's lawyers, was broadcast on the Sunday Night documentary slot of Australia's Channel Seven.

It shows Pistorius running on his stumps towards the camera, with one arm outstretched as if holding a gun.

In another sequence he is seen carrying a woman from the bathroom.

As he re-enacts the sequence of events which lead to the death of his girlfriend Reeva Steenkamp, he is heard explaining to investigators: "I heard the noise and fired four shots."

He claims he had first warned what he believed was an intruder in the bathroom shouting: "I'll call the police, get out, get out! Get the f*** out!"

The paralympian can then be heard screaming and shouting hysterically "'Please, God, please, please help. Help me. Help me!" after he opened the door to find his girlfriend dead on the bathroom floor.

Oscar Pistorius
The athlete recreates how he found Reeva Steenkamp slumped over the toilet after he shot her.Seven Network / Sunday Night

In another part of the video, the athlete is seen slumped over the toilet with his legs splayed on the floor, just as he found his girlfriend 'bleeding to death' after he beat down the bathroom door with a cricket bat.

The footage shows him struggling to balance as he carries the woman down the stairs.

It is believed that the video re-enacting the scene of Steenkamp's death was produced for Pistorius's defence team, and was intended to construct a picture of a man who was extremely vulnerable on the night of the shooting, and in fear of an intruder, because he couldn't run away.

Clips of the footage have been aired on news networks in the US prompting the fallen sports star's legal team to demand action against "staggering breach of trust and an invasion of the family's privacy".

They have asked for "urgent clarification" from Channel Seven in Australia, which has been broadcasting a trailer of the video before showing it on its current affairs programme Sunday Night.

In a statement Pistorious's legal team said: "In October 2013, the Defence Team engaged the services of The Evidence Room, A US-based company specialising in forensic animation," the statement said.

"The company was engaged to visually map the events on the night of the accident. As part of this process, certain video footage was filmed.

"The 'visual mapping' was for trial preparation only and was not intended to be used for any other purpose.

Oscar Pistorius
Pistorius demonstrates how he carried Reeva's body out of the bathroom.Seven Network / Sunday Night

"It has now emerged that an Australian broadcaster has obtained some of this footage from The Evidence Room and has just gone to air with it.

"We wish to make it very clear that the material that has been aired was obtained illegally and in breach of the non-disclosure agreement with The Evidence Room.

"Its usage also constitutes a breach of privilege as this material was produced for trial purposes on the instructions of a commissioner, and the ownership of the copyright vests in the commissioner. No permission for the disclosure thereof has been given."

The video has not been presented in court.

Pistorius, who is on trial for premeditated murder, denies deliberately killing his girlfriend, claiming he mistook her for an intruder.

He faces between 25 years and life in prison if found guilty.