A South African magistrate has postponed the murder trial of Oscar Pistorius until 19 August after lawyers asked for time to prepare for the case.

The 26-year-old Olympic and Paralympic track star, a double amputee since infancy, is accused of the premeditated murder of 29-year-old Reeva Steenkamp in February.

In pre-trial testimony, his lawyers said the shooting was a tragic mistake and Mr Pistorius was acting in self-defence against what he thought was an intruder.

Mr Pistorius made his way through a scrum of photographers and reporters for his first formal public appearance since his release on bail in February.

A judge changed his bail conditions in March, granting him permission to travel abroad.

In an interview shown on South African television last night, Ms Steenkamp's parents Barry and June said they were desperate to find out why their daughter had been shot.

In the Channel 5 interview, Mrs Steenkamp said "there is only one person who knows what happened" that night in February when her "terrified" daughter was killed.

Mr Pistorius's family yesterday said they will "support him every step of the way" and "fully stand behind" him.