South African state prosecutors have said they will appeal a culpable homicide verdict and five year jail term handed down to fallen track star Oscar Pistorius last week.

"NPA (National Prosecuting Authority) will be appealing both the conviction and sentence," spokesman Nathi Mncube said.

Pistorius, whose lower legs were amputated as a baby but who ran on carbon fibre prosthetic limbs, was convicted of culpable homicide last month for the shooting of Reeva Steenkamp, a 29-year-old law graduate and model, at his luxury Pretoria home.

Prosecutors failed to prove murder after the athlete said he fired in the mistaken belief an intruder was hiding behind the door, a defence that struck a chord with many people in a country with one of the world's highest rates of violent crime.

However, Judge Thokozile Masipa's decision drew criticism from some legal experts who said she had made an error in her interpretation of the legal concept of 'dolus eventualis', whereby a person is held accountable for the foreseeable consequences of their actions.

Other lawyers said her verdict was sound.

In South Africa, an appeal by the state against a verdict can only be made on a matter of law, and does not involve a retrial or the submission of any new evidence.