(JOHANNESBURG) -- Former South African President Nelson Mandela was admitted to the hospital just before midnight Wednesday due to his recurring lung infection, the South African President's office said on Thursday.
"Doctors are attending to him, ensuring that he has the best possible expert medical treatment and comfort," the government's statement said.
Mandela, 94, spent 18 days in the hospital in December for a lung infection and gallstones.
"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. We have full confidence in the medical team and know that they will do everything possible to ensure recovery," South African President Jacob Zuma said in the statement.
The anti-Apartheid activist was admitted to a Pretoria hospital on March 10 for routine medical tests and to "manage existing conditions in line with his age," a spokesman for the South African President's office said.
Despite rare public appearances, Mandela, who is credited with changing race relations in South Africa, remains hugely popular in the country.
In November 2012, banknotes featuring Mandela's image were printed and entered into circulation in South Africa.
After enduring nearly three decades of prison, much of it at hard labor in a lime quarry, Mandela emerged as a gentle leader who was elected South Africa's first black president in 1994.
He was awarded the Nobel Peace Prize for his leadership in ending apartheid without violence, and later became a global statesman who inspired millions of people around the world.
After he left office in 1999, Mandela became a global statesman, mediating conflicts in some of the world's most troubled spots.
He has since retired to his childhood home in Qunu. Occasionally, the government has released photos of the former president after high-profile visitors meet with him in Qunu.
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