Former South African President Nelson Mandela been re-admitted to hospital with a recurring lung infection. Mr Mandela was admitted just before midnight a statement from the South African presidency said.
The 94-year-old anti-apartheid leader is being treated for a "recurrence of his lung infection" and doctors are ensuring he has the best possible treatment, the statement said. South African President Jacob Zuma wished Mr Mandela a speedy recovery and appealed for prayers.
"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," he said. The former president is often fondly referred to by his clan name, Madiba.
Mandela has been admitted to hospital several times since last year, most recently earlier this month when he received what a presidential spokesman described as a "successful" medical test.
"Doctors are attending to him, ensuring that he has the best possible expert medical treatment and comfort," the Zuma statement said. It appealed "for understanding and privacy in order to allow space to the doctors to do their work".
Late last year Mr Mandela spent three weeks in hospital being treated for a lung infection and gallstones. A year ago, he was admitted to a Johannesburg hospital for what officials initially described as tests but what turned out to be an acute respiratory infection. He was discharged days later. He had surgery for an enlarged prostate gland in 1985.
Under South Africa's white-minority apartheid regime, Mandela served 27 years in prison, where he contracted tuberculosis, before being released in 1990. He later became the nation's first democratically elected president in 1994 under the banner of the
African National Congress, helping to negotiate a relatively peaceful end to apartheid despite fears of much greater bloodshed. He served one five-year term as president before retiring.
Mandela last made a public appearance on a major stage when South Africa hosted the 2010 World Cup.