Witnesses heard arguing, a woman screaming and gunfire at the house of "Blade Runner" Oscar Pistorius the night he shot dead his model girlfriend, police told a South African court today.

Pistorius's defence team played down the reliability of the claims as the South African sporting hero sought bail for the Valentine's Day killing that he insists was a horrible accident and not intentional, as prosecutors aim to prove.

Police also said Pistorius had previously been arrested at his Pretoria home for assault, although he was not charged, and faced further charges of possessing an unlicensed gun.

A woman who lives in the same highly secured complex as Pistorius "heard talking that sounded like non-stop fighting from two to three in the morning," hours before she was killed, Prosecutor Gerrie Nel said.

Another witness reported hearing gunshots, screams and then more shots, police said.

"We have the statement of a person who said after he heard gunshots, he went to his balcony and saw the light was on. Then he heard a female screaming two-three times, then more gunshots," Detective Hilton Botha said.

But Pistorius's legal team disputed these accounts as police said the witnesses were at least 300 metres (nearly 990 feet) from the house.

And the prosecution, which wants to prove that the Paralympian had deliberately planned to kill Reeva Steenkamp, was forced to admit that Pistorius's claim that he mistook her for an intruder matched the crime scene.

"It sounds consistent," Botha said.

Steenkamp, a 29-year-old model, was shot three times through the bathroom door early on February 14, with wounds to her head, elbow and hip.

She was declared to have died later by medics who found her covered in bloodied towels and wearing white shorts and a black vest.

Botha was forced to admit police had missed a bullet that hit the toilet basin in their investigation and which the defence's forensic team discovered four days later.

Botha also conceded he did not wear protective clothing in his inspection, which may have contaminated the scene.

Pistorius, the first double amputee to compete against able-bodied athletes in the Olympics in London last year, says he shot Steenkamp by mistake through a locked bathroom door, believing she was a burglar.

"I had no intention to kill my girlfriend," he said in an affidavit read to the court on the first day of his bail hearing Monday.

The 26-year-old said he kept a firearm under his bed at night because he had been a victim of violence and burglaries before and had received death threats.

But the state prosecutor said the athlete would face an additional charge of possessing unlicensed .38 special calibre ammunition.

A police search of his home also found testosterone and needles in a dresser in his bedroom, Botha said.

Defence lawyer Barry Roux however said the sex hormone was an acceptable supplement. "It's a herbal remedy and he can use it and he has used it before," he said.

The International Paralympic Committee (IPC) announced that Pistorius was drug-tested before and during last year's Paralympic Games in London and on both occasions the results were negative.

But the International Olympic Committee said they did not test Pistorius during the Olympics and did not have his samples.

Magistrate Desmond Nair said earlier he could not rule out that there was some planning involved in the killing, which may be considered as a premeditated murder, setting a high bar for bail.

The bail hearing was adjourned until Thursday.

Pistorius's defence team and family looked confident at the end of Tuesday's session while the prosecution's lawyers held worried discussions.

The athlete, who off the track has had a rocky private life with stories of rash behaviour, beautiful women, guns and fast cars, has built up a powerful team of lawyers, medical specialists and public relations experts for his defence.