JOHANNESBURG (Reuters) - South African state prosecutors will approach the Supreme Court of Appeal for leave to challenge Oscar Pistorius' six-year murder sentence after failing with a similar bid at a lower court, the National Prosecuting Authority said on Thursday.

State prosecutors, led by advocate Gerrie Nel, will file an application to appeal on Friday, NPA spokesman Luvuyo Mfaku told Reuters.

Judge Thokozile Masipa dismissed a request by state prosecutors to appeal Pistorius' sentence last month, saying she was not persuaded that there was a reasonable prospect of success at another court.

Pistorius was sentenced to six years in prison after being found guilty of murdering his girlfriend Reeva Steenkamp on appeal last December. He had initially received a five-year sentence for manslaughter in 2014.

The jail term was less than half the 15-years sought by prosecutors, who said Pistorius had shown no remorse for the 2013 shooting.

(Reporting by Tanisha Heiberg; Editing by Joe Brock)