A lawyer for Oscar Pistorius says South Africa's highest court has dismissed the former track star's appeal of his murder conviction.

The ruling by the Constitutional Court on Thursday clears the way for a judge to sentence Pistorius for murder at a hearing scheduled for April 18.

Defense lawyer Andrew Fawcett confirmed the Constitutional Court's decision and said: "We'll proceed to the sentencing."

Pistorius, who killed girlfriend Reeva Steenkamp in his home in 2013, had appealed to the Constitutional Court, saying another court erred when it overturned a manslaughter conviction and declared the Olympic athlete guilty of murder.

The minimum sentence for murder in South Africa is 15 years, though a judge can reduce that sentence for what the law describes as exceptional circumstances. Pistorius is currently under house arrest.