CAPE TOWN, South Africa -- Prosecutors in the Oscar Pistorius case will add two firearm charges believed to relate to recklessly firing guns in public to the indictment against the double-amputee athlete, who is already due to go on trial for murder and illegal possession of ammunition.

National Prosecuting Authority spokesman Nathi Mncube told The Associated Press that Pistorius' lawyers received a letter on Tuesday advising them that the charges would be added and Pistorius also would face them at his trial in March next year.

Mncube said the additional charges were already raised against Pistorius but were not in the original indictment served to him in August because these offences are alleged to have occurred in the Johannesburg region, a different court jurisdiction to Pistorius' fatal shooting of girlfriend Reeva Steenkamp in the South African capital, Pretoria, on Feb. 14.

Prosecutors had to seek permission from South Africa's new National Director of Public Prosecutions to "centralize" all the charges, Mncube said, so they all could be heard in the same trial at the North Gauteng High Court in Pretoria. Pistorius' murder trial is due to start Mar. 3.

"The National Director has indeed given them (prosecutors) that authority and they will be added," Mncube said. "They are not new charges, they were charges that already existed. They were just in a different jurisdiction."

Mncube declined to detail the charges, only saying there were two additional counts and they covered "the contravention of the firearm controls act."

Pistorius' spokeswoman Anneliese Burgess told the AP that the Pistorius family did not want to comment on "legal aspects" of the case while a member of Pistorius' legal team did not immediately answer telephone calls from the AP.

The South African media has reported that Pistorius has twice shot a gun in a public place: One out of a moving car when he was driving with a former girlfriend and another at a restaurant in Johannesburg when he apparently accidentally fired a friend's gun under a table.

The National Prosecuting Authority would not comment on any of the details surrounding the two charges to be added, but people who are believed to have been present at the two incidents were included in the prosecution's list of more than 100 witnesses when Pistorius was indicted just over two months ago.

The 26-year-old Olympic runner faces a life sentence with a minimum of 25 years in prison if he is convicted on the main charge of premeditated murder in the shooting death of Steenkamp in the pre-dawn hours of Valentine's Day.

Pistorius denies murder and says he shot Steenkamp in self-defence through a toilet door with his licensed 9mm handgun, thinking mistakenly that she was a dangerous intruder in his upscale Pretoria villa. Prosecutors believe he intended to kill her, possibly after a loud argument in the middle of the night.