President Jacob Zuma told parliament that he is happy with the progress that Mandela is making "following a difficult last few days."
The 94-year-old former president was admitted to a Pretoria hospital on Saturday. It's the fourth time Mandela has been hospitalized for treatment since December.
Zuma noted that Wednesday marked the 49th anniversary of the sentencing of Mandela to life in prison in 1964. He said "our thoughts" are with Mandela and his family "on this crucial historical anniversary."
Mandela has been vulnerable to respiratory problems since contracting tuberculosis during 27 years as the prisoner of the white racist government. Most of that time was spent on Robben Island, off the coast of Cape Town, where Mandela and other prisoners spent part of the time toiling in a stone quarry.
He was freed in 1990, and then embarked on peacemaking efforts during the tense transition that saw the demise of the apartheid system and his own election as South Africa's first black president in 1994.
Outside Mandela's Johannesburg home, well-wishers continued to leave tributes to the former president.
The Associated Press contributed to this report.
