An emotional Oscar Pistorius broke down in tears today as he was found not guilty of the second-degree murder of girlfriend Reeva Steenkamp by a judge in South Africa.

He was also cleared of the more serious charge of pre-meditated murder.

He faces a remaining charge of culpable homicide - the South African equivalent of manslaughter - as well as firearms offences.

Ms Steenkamp was killed at double-amputee Pistorius' home on February 14, 2013.

Pistorius, aged 27, said he thought his girlfriend was in his bedroom and that intruders were in his bathroom when he fired four shots.

Delivering her verdicts, Judge Thokozile Masipa said: "The accused believed his life was in danger. The accused cannot be found guilty of murder."

Pistorius sat sobbing with his head bowed in court as Judge Masipa read the verdicts. He sat alone on a bench seat in the hushed court room.

The judge said she believed accounts that an emotional Pistorius gave to police at the scene in the moments after the shooting.

She said: "Counsel for the defence correctly argued that it was highly improbable that the accused would have made this up so quickly and be consistent in his version, even at the bail application, before he had access to the police docket and before he was privy to the evidence on behalf of the state at the bail application.

"The question is, did the accused foresee the possibility of the resultant death, yet persisted in his deed reckless of whether death ensured or not?

"In the circumstances of this case, the answer has to be no.

"How could the accused reasonably have foreseen that the shot he fired would kill the deceased? Clearly he did not subjectively foresee this as a possibility that he would kill the person behind the door, let alone the deceased - as he thought she was in the bedroom at the time. "

Earlier, judge Masipa said there was insufficient evidence to support the prosecution's claim that the double-amputee intended to kill his law graduate girlfriend.

She said: "The state clearly has not provided beyond reasonable doubt that the accused is guilty of pre-meditated murder.

"There are just not enough facts to support such a finding."

But the judge also described Pistorius as a "very poor witness", saying he "lost his composure" during cross-examination.

The 27-year-old could still be convicted of negligent killing. He could also be acquitted if Ms Masipa believes he made a tragic error.

The judge will deliver her final verdicts after a lunch break.

Pistorius attended court after wading through a media scrum, packed with camera crews and photographers.

Before the session began, Pistorius hugged his brother Carl, who was seated in a wheelchair because of injuries suffered in a recent car crash.

Ms Steenkamp's parents were also in the packed gallery. Other members of Pistorius' family, including his father Henke, sat behind him.

Delivering her verdict, the judge said some witnesses had failed to separate their own evidence from details contained in press coverage, acknowledging the way the trial had been televised. It is seen as a landmark case in the South African judicial system.

If Pistorius is convicted on any charge, including those involving firearms, the case will likely be postponed until a later sentencing hearing.

It is more than 18 months since Pistorius shot dead Ms Steenkamp at his luxury home on Valentine's Day 2013. Judge Masipa determines the defendant's fate as South Africa does not have trial by jury.

In one night Pistorius was transformed from a global sporting hero to murder suspect. A little more than six months before the shooting, he made history at London 2012 by becoming the first amputee sprinter to compete in the Olympic Games.

Then in the early hours of February 14 2013, the athlete - who had his lower legs amputated as a baby - fired his 9mm pistol through a closed toilet door at his home in Pretoria. Ms Steenkamp, 29, suffered fatal injuries after she was hit in the head, arm and hip.

Interest in the subsequent case, which opened in March this year, was intense and a ruling that parts of the trial could be broadcast live on television added to the scrutiny.

It opened in March with a witness describing how she heard "bloodcurdling screams" on the night of the shooting.

The prosecution, led by Gerrie Nel - nicknamed The Bulldog for his courtroom tenacity - sought to depict the star as having a short fuse and being obsessed with guns, calling a former girlfriend who told the trial that the defendant once shot his gun out of the sunroof of a car.

His defence team, headed by Barry Roux, presented a case that portrayed him as anxious about crime and claimed evidence at the scene was mishandled.

The trial's tensest and most dramatic moments came in several days of highly charged testimony from Pistorius.

His voice thick with emotion, the athlete began his evidence by saying sorry to Ms Steenkamp's family.

Watched by the model's mother June, he said: "I was simply trying to protect Reeva. I can promise that when she went to bed that night she felt loved."

Mrs Steenkamp later told Hello! Magazine she has forgiven him.

Pistorius was on the stand for five days of intense cross-examination from Mr Nel. At one point he refused to look at a photograph of Ms Steenkamp's wounds as the prosecutor urged him to "take responsibility".

In June, after the trial was halted for a month, experts concluded that Pistorius was not suffering from mental illness at the time of the shooting.

In a tweet on August 8, Pistorius wrote: "Thank you to my loved ones and those that have been there for me, who have picked me up and helped me through everything."