JOHANNESBURG (Reuters) - South Africa's Supreme Court of Appeal (SCA) on Friday told state prosecutors and the defense to argue their case over the six-year sentence for murder handed to Paralympic gold medalist Oscar Pistorius in open court.

Pistorius was sentenced to six years in prison in July after being found guilty of murdering his girlfriend Reeva Steenkamp on appeal last December, in a case that has attracted worldwide interest.

Legal experts had expected the SCA to issue a ruling on whether prosecutors have the right to challenge the sentence but instead said both parties should first argue their case in court. The court did not set a date for the appeal hearing.

State prosecutors, led by advocate Gerrie Nel, say the sentence was too lenient as the jail term was less than half the 15-years they sought. In his arguments at the trial, Nel said Pistorius had shown no remorse for the 2013 shooting.

Lawyers for the gold medalist, known as the "Blade Runner" for his carbon-fiber prosthetics, say he did not deliberately kill model and law graduate Steenkamp.

The athlete originally received a five-year sentence for a manslaughter conviction, that was upgraded to murder on appeal.

Trial Judge Thokozile Masipa, who sent Pistorius to the six-year jail term, dismissed a request by Nel to appeal Pistorius' sentence, saying she was not persuaded that there was a reasonable prospect of success at another court.

Nel then launched his case at the SCA, in Bloemfontein, 400 km (250 miles) southwest of Johannesburg.

(Reporting by Mfuneko Toyana; Editing by James Macharia)