Oscar Pistorius’s six-year jail sentence for killing his girlfriend Reeva Steenkamp has been increased to more than 13 years.

The Supreme Court of Appeal (SCA) on Friday set aside the six-year imprisonment sentence imposed on the former Paralympic athlete by the Pretoria High Court last year and replaced it with 13 years and five months.

The National Prosecuting Authority (NPA) had approached the SCA asking it to increase Pistorius’s sentence‚ arguing that the sentence he was serving for killing his girlfriend was "shockingly low".

Pistorius shot his girlfriend dead in the early hours of Valentine's Day in 2013‚ when he fired four times through the door of his toilet - an act‚ he says‚ that came from mistaking her for a burglar.

Pistorius was originally convicted of culpable homicide in 2014‚ but the SCA upgraded his conviction to murder in 2015. In July last year the Pretoria High Court sentenced him to six years’ imprisonment for the murder of Reeva Steenkamp.

The appeal court said his testimony was “vacillating and untruthful”.

Prosecutor Andrea Johnston had argued that Pistorius did not show remorse and had not told the Pretoria High Court why he had shot Steenkamp. “He should have taken the court into his confidence and said‚ ‘This is why I did it’. With nothing more‚ there is no gut-wrenching remorse.”

Johnston told the court that trial judge Thokozile Masipa elevated Pistorius’s regret and that his regret does not absolve him from the crime he committed.

Advocate Barry Roux‚ counsel for Pistorius‚ argued that his client had showed more than remorse. “His actions were directed against the intruder. When he realised he had shot Reeva‚ he was beside himself.”

“His whole concern was about the deceased and her family. He tried to make contact before and during the trial. After the trial‚ he tried to make contact‚” Roux argued.