Oscar Pistorius, the South African Paralympic gold medallist serving a six-year jail term for murdering his girlfriend, was taken to hospital on Thursday, a prison service spokesman said.
The prison service provided no details of Pistorius's illness, but a spokesman, Logan Maistry, said he would be kept in hospital overnight for observation. He said he could not comment on a report by the Citizen website that Pistorius suffered chest pains and prison staff suspected a heart attack.
"I am not aware of (that report) or what he suffered from," Maistry said. "What I am aware of is that he was this morning taken to an outside hospital for a medical examination ... "
Last August, Pistorius denied trying to kill himself after he was treated in hospital for wrist injuries.
The athlete was sentenced to six years in prison in July last year after being found guilty of murdering his girlfriend, Reeva Steenkamp, on Valentine's Day 2013.
He reached the pinnacle of his fame in 2012 when he became the first double amputee to run in the Olympics, making the 400 metres semi-finals in London before taking two golds in the Paralympics.
Pistorius' family spokeswoman was not immediately available to comment.