Apartheid-era foreign affairs minister Pik Botha is in a stable condition and is currently under supervision at Netcare Akasia Hospital in Pretoria North, the hospital said.
"We can't really comment on the details, because of patient confidentiality, but we can say that he was admitted for heart failure and is still being treated at the hospital," the hospital's general manager Priscilla Botha said.
She said staff at the hospital was keeping an eye on the situation.
Pik has lung condition
The 76-year-old former politician was admitted after he struggled to breathe while on holiday with his wife Ina.
Ina told SABC radio that his heart failed because of the condition of his lungs.
"The lungs are a problem because decades of smoking didn't do him any good. The situation in his lungs can't be reversed," she said.
"As far as the heart is concerned, we will consult with a cardiologist after his discharge, and then take it from there."
Botha should quit smoking
Doctors reportedly advised him to quit smoking or face further cardiac problems.
Botha served as foreign affairs minister in the last years of the apartheid government and served as minister of mineral and energy affairs under Nelson Mandela, South Africa's first democratically elected president.
He retired from politics in 1996 when the National Party withdrew from the government of national unity.
In 2000, he announced that he would join the African National Congress.
(Sapa, September 2011)