The disgraced former South African athlete was allegedly involved in a fight over the use of a public phone, a prison department spokesman has said.

Pistorius, who was jailed for 13 years and five months, sustained only minor injuries in the incident, with reports that he received only 'a bruise'.

"It is alleged that he was involved in an altercation with another inmate over the use of a public phone in the special care unit where both offenders are detained at Attridgeville Correctional Centre," the spokesman, Singabakho Nxumalo, said.

An investigation has been launched, which is standard procedure, to: "establish the facts and to ensure that appropriate action is taken as incidents of assaults are not allowed", Nxumalo added.

The brawl reportedly took place on December 6, 10 days after South African prosecutors successfully argued Pistorius' "shockingly light" six-year sentence should be increased.

In November, the Supreme Court of Appeal gave Pistorius the minimum 15 years prescribed for murder in South Africa, less time already served.

The Paralympian  was initially found guilty of manslaughter after he claimed he shot Steenkamp through a locked bathroom door having mistaken her for a burglar in the early hours of Valentine's Day in 2013.

But the Supreme Court of Appeal overturned the ruling in 2015, and found him guilty of murder.

Pistorius made history by becoming the first amputee sprinter to compete at the Olympics, in 2012 in London, running on prosthetic "blades".