South African prosecutors have officially filed an appeal against Oscar Pistorius's verdict and sentence for killing his girlfriend Reeva Steenkamp.

The 27-year-old was sentenced to five years in prison for the culpable homicide of Steenkamp, whom he shot dead through a toilet door.

The six-time Paralympic champion was cleared of murder after claiming that he mistook Steenkamp for an intruder when he fired four gunshots at his home in Pretoria, South Africa in the early hours of Valentine's Day last year.

The state expressed its disappointment after Pistorius escaped murder and now has officially appealed the verdict as well as the sentence, after it was reported that the athlete would spend 10 months behind bars before serving the rest of his sentence under house arrest.

The National Prosecuting Authority said: "Today, we announce that the NPA filed the application for leave to appeal both the conviction and sentence. The appeal on conviction is based on the question of law."

Pistorius's defence team have not appealed Judge Thokozile Masipa's verdict or sentence.