South Africa's president says that Nelson Mandela is seeing sustained improvement from the recurring lung infection that is forcing him to spend a ninth day in the hospital.

President Jacob Zuma said Sunday that Mandela remains in serious condition but that over the last two days his doctors have said that the improvements in his health have been sustained. Zuma said that Mandela "continues to engage with family."

Speaking at a Youth Day celebration in South Africa, Zuma asked the audience to join him in wishing Mandela a happy Father's Day.

The leader of South Africa's anti-apartheid movement, Mandela spent 27 years in prison during white racist rule. He was freed in 1990 and became South Africa's first black president in 1994.