A civil rights organisation claims that an inmate at Groenpunt prison in the Free State died on Sunday after he was refused treatment for Covid-19.
But correctional services officials denied that the man had the disease and said an autopsy would be conducted to determine the cause of his death.
According to SA Prisoners Organisation for Human Rights president Golden Miles Bhudu, the man was denied treatment and an official allegedly commented that he had Covid-19.
"The male nurse that came along with them said these words: 'I will not take you to the hospital unit because you will infect other inmates in the hospital with Covid-19'," Bhudu said.
Department of Correctional Services spokesperson Singabakho Nxumalo confirmed that the inmate died, but said he definitely did not have Covid-19.
"Our healthcare official went through his medical file and assured us that it could not have been a Covid-related case," said Nxumalo.
He said the department took seriously the allegation that the inmate might not have received proper care and added that the matter was under investigation.
An autopsy will be conducted to establish the cause of the inmate's death.
Bhudu said inmates were afraid of contracting the virus, but there was little they could do.
On Monday, the department said an East London women's prison official was admitted to hospital after testing positive for Covid-19.