South African prison authorities said Tuesday that Oscar Pistorius, a double-amputee track star jailed for murdering his girlfriend, Reeva Steenkamp, had been bruised in an altercation with a fellow inmate over the use of a public telephone in prison.

While Pistorius, 31, was not seriously injured, prison authorities said the events were under investigation. News reports said that Pistorius, who competed in both the Olympic and Paralympic Games in London in 2012, could lose privileges if found to have started the fight.

The episode was said to have taken place at the Atteridgeville Correctional Center, near Pretoria, which has facilities for disabled prisoners. Pistorius was born without fibulas and his legs were amputated below the knee when he was less than a year old. He has competed using curved prostheses that inspired the nickname Bladerunner.

Singabakho Nxumalo, a spokesman for the Department of Correctional Services, told South African news outlets that the altercation happened last Wednesday in a special care unit where Pistorius and another prisoner were incarcerated. During a medical checkup later, Pistorius was found to have been bruised. The other person involved in the fight was not identified by name.

It is “standard operating procedure regarding cases of alleged assaults” to hold an inquiry to “establish the facts and to ensure that appropriate action is taken as incidents of assault are not allowed,” Nxumalo said.

Some South African news reports said other prisoners thought Pistorius spent too much time on the shared telephone.

The reported brawl came less than two weeks after the Supreme Court of Appeal more than doubled the jail term a lower court had imposed on Pistorius for the killing of Steenkamp, a model who had a law degree.

The case has drawn abiding attention in South Africa and internationally. Pistorius and Steenkamp had been dating for only a few months, but they were a celebrity couple, embodying glamour and, in Pistorius’ case, an ability to prevail over physical hardship. The hearings also touched on questions of race and violence against women — perennial, troubling themes in South Africa.

Pistorius denied committing murder, saying he opened fire through a locked bathroom door at his home in Pretoria in the early hours of Feb. 14, 2013, in the belief that an intruder had entered the building, only to discover that he had shot and killed Steenkamp. The prosecution maintained that he had opened fire in a jealous rage after an argument.

Initially, a High Court judge found him guilty of the South African equivalent of manslaughter, but the prosecution appealed and the conviction was changed to murder. He was initially jailed in July 2016 for six years, a sentence that the prosecution appealed as “shockingly lenient.”

Last month, after a further appeal, his prison term was more than doubled. He now has more than 13 years left to serve. The judges who heard the appeal said the initial sentence was “shockingly lenient, to a point where it has the effect of trivializing this serious offense.”

The written ruling found that Pistorius “displays a lack of remorse and does not appreciate the gravity of his actions.”