South African Paralympic gold medallist Oscar Pistorius was sent to prison for six years on Wednesday for the 2013 murder of his girlfriend, Reeva Steenkamp, the latest twist in a trial that has gripped the world.

The state and large sections of the South African public had called for him to receive no less than the prescribed minimum 15-year sentence for murder, saying Pistorius had shown no remorse for the killing.

Judge Thokozile Masipa disagreed, accepting the defence's arguments for a lesser punishment.

"Public opinion may be loud and persistent but it can play no role in the decision of this court," Masipa said. "I am of the view that a long term in prison will not serve justice."

It was not clear whether the state would appeal the verdict.

Dressed in a dark suit, the 29-year-old stared straight ahead as Masipa read out the sentence.

Pistorius was found guilty of murdering Steenkamp by an appeals court last December. He had initially received a five-year sentence for a manslaughter conviction in 2014 handed down by Masipa, a ruling derided by women's groups as too lenient.

In her ruling on Wednesday, Masipa said that although the Steenkamp family had suffered great loss, Pistorius' life and career was also in ruins.

"The life of the accused shall also never be the same. He is a fallen hero and can never be at peace," she said.

The athlete had the lower part of his legs amputated when he was a baby and his lawyers argued that his disability and mental stress should be considered as mitigating circumstances to reduce his sentence.

Pistorius was freed from prison last October after almost a year behind bars to serve out the remainder of his five-year term under house arrest at his uncle's house in a wealthy suburb of the capital.

Some rights groups have said Pistorius, a wealthy white man and international celebrity, has received preferential treatment compared to others without his status or wealth.

He argued that he fired four shots into the door of a toilet cubicle at his luxury Pretoria home in the mistaken belief that an intruder was hiding behind it.

Members of the Women's League of the ruling African National Congress (ANCWL), who have attended the trial in support of the murdered Steenkamp, said the sentence handed down by Masipa was not sufficient.

"First five years, now six years? She is an embarrassment to the justice system," ANCWL spokeswoman Jacqueline Mofokeng said of Masipa. "It is an insult to women in this country."

Outside the court, a group of people held up placards backing the athlete. One read: "Give Oscar his freedom back please".

Steenkamp's father Barry, who said during sentencing hearings that Pistorius must pay for his crime, declined to comment on the prospects for an appeal.

"We'll leave that to the state," he told reporters. – Reuters