Convicted paralympic athlete Oscar Pistorius may end up spending only 10 months in prison for the culpable homicide of his girlfriend Reeva Steenkamp, a justice department spokesman said on Tuesday.

"Five years in terms of [Section] 276 of the Criminal Procedure Act means the accused serves one-sixth of the sentence, which is 10 months," spokesman Mthunzi Mhaga said on his Facebook wall referring to the sentence handed down to Pistorius in the High Court in Pretoria.

"And an offender or inmate can be considered for placement under correctional supervision which is processed by correctional services."

Pistorius was sentenced to five years in prison after being found guilty of culpable homicide. For discharging a firearm at Tasha's restaurant in January 2013, he was sentenced to three years in jail, suspended for five years.

Both sentences would run concurrently, Judge Thokozile Masipa ruled.

On September 12, Masipa found Pistorius guilty of Steenkamp's culpable homicide, but not guilty of her murder.

Pistorius had claimed he thought there was a burglar in his toilet when he fired four shots through a locked door in the early hours of February 14 last year, killing Steenkamp. The incident happened at his Pretoria home.

Masipa also found Pistorius guilty of discharging a firearm in public, when he shot from his friend Darren Fresco's Glock pistol under a table at Tasha's restaurant in Melrose Arch, Johannesburg, in January 2013.

Pistorius was found not guilty on two firearms-related charges - illegal possession of ammunition, and shooting through the open sunroof of a car with his 9mm pistol while driving with friends in Modderfontein on September 30, 2012.