Nelson Mandela is being treated for a lung infection, and is responding to the treatment, the Presidency said in an update on the former president's health on Tuesday.
Mandela was admitted to an undisclosed hospital in Pretoria on Saturday in order to undergo tests.
"Doctors have concluded the tests, and these have revealed a recurrence of a previous lung infection, for which Madiba is receiving appropriate treatment, and he is responding to the treatment," the Presidency said in a statement.
President Jacob Zuma "thanks the public for continuous support to former President Mandela and his family at this time," the Presidency added.
Zuma visited Mandela at the hospital in Pretoria on Sunday, after which he assured South Africans that the Madiba was doing well and that there was no cause for alarm.
"He found him comfortable, and in good care," the Presidency said, as it appealed to the media and the public to respect the privacy of Mandela and his family.
Mandela, who turned 94 in July, underwent treatment for a similar respiratory infection at Johannesburg's Milpark Hospital in January 2011.
"We wish Madiba all the best," Zuma said. "The medical team is assured of our support as they look after and ensure the comfort of our beloved founding president of a free and democratic South Africa."