Former South African President Nelson Mandela was admitted to hospital after a recurrence of a lung infection, the South African president's office said Thursday.
The Nobel laureate was admitted to hospital on Wednesday night.
"Doctors are attending to him, ensuring that he has the best possible expert medical treatment and comfort," President Jacob Zuma's office said in a statement.
"We appeal to the people of South Africa and the world to pray for our beloved Madiba and his family, and to keep them in their thoughts," the statement said.
Madiba refers to his affectionate clan name, which is widely used in the nation.