Local media reported that the 30-year-old double-amputee was suffering from chest pains and was taken by ambulance to the emergency department at Kalafong Hospital.
The 30-year-old, now serving a six-year prison sentence for murder, was taken to a medical facility in South Africa on Thursday and kept in overnight for tests.
"We can state that offender Oscar Pistorius was taken to an outside hospital facility this morning for a medical examination, and is expected back in the facility later today", the prison official told South Africa's The Citizen newspaper. However, Pistorius will now stay overnight in the hospital "for observation", Maistry said.
This is not the first time Pistorius required medical treatment during his time behind bars.
Pistorius initially began serving his prison sentence at Kgosi Mampuru II, but was later moved to Atteridgeville since that prison is better equipped to handle prisoners with disabilities. Previous year he was taken to the hospital for treatment to cuts on his wrists, which prison authorities said he sustained after falling in his cell.
Dubbed the "Blade Runner", Pistorius soared to global fame after becoming the first amputee to compete against able-bodied athletes in the 2012 Olympic Games.
Pistorius has served a year of his sentence.
His trial became the subject of widespread worldwide attention, as he was initially cleared of murder in favour of a manslaughter charge - then convicted of murder on appeal in 2016.
Neither prison authorities nor Pistorius' family have confirmed the cause of his chest pains. Pistorius' uncle Arnold also told the news outlet that Oscar had just suffered a "couple of bruises" from the incident.
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