South Africa's Constitutional Court has rejected Oscar Pistorius' last-ditch attempt to appeal against his murder conviction for shooting dead his girlfriend Reeva Steenkamp, an official said this afternoon.

The Olympic and Paralympic athlete has been on bail awaiting a new sentence since December, when the Supreme Court of Appeal (SCA) found him guilty of murder.

The SCA overturned his earlier conviction on the lesser charge of culpable homicide.

Pistorius' lawyers had applied for leave to appeal to the Constitutional Court, the highest court in South Africa, arguing that the SCA had "acted unlawfully and unconstitutionally".

But the National Prosecuting Authority (NPA), which opposed the application, said the appeal attempt had failed.

"The court dismissed the application for leave to appeal because there are no prospects of success," NPA spokesman Luvuyo Mfaku said.

Mr Mfaku said the court's decision had been made yesterday.

Pistorius, 29, could face at least 15 years in jail when he attends a sentencing hearing on 18 April.

The double-amputee killed Ms Steenkamp, a model and law graduate, in the early hours of Valentine's Day three years ago, saying he mistook her for an intruder when he shot four times through the door of his bedroom toilet.