JOHANNESBURG // The former South African president, Nelson Mandela, was "responding positively" to treatment for a recurring lung infection after being admitted to hospital during the night, the government said yesterday. Mr Mandela, who became South Africa's first black president in 1994, has been mostly absent from the political scene for the past decade, but he remains an enduring symbol of the struggle against racism. "He remains under treatment and observation in hospital," the government said, without giving details about the health of the 94-year-old anti-apartheid leader. He is renowned around the world for spending 27 years in prison fighting the last bastion of white rule in Africa and then promoting the cause of racial reconciliation. But he has been frail and in poor health for several years. He spent nearly three weeks in hospital in December with a lung infection and after surgery to remove gallstones. He was also admitted briefly to hospital this month for a check-up. Mr Mandela has a history of lung problems dating back to when he contracted tuberculosis as a political prisoner. As he has stepped back from public life, critics say his ruling African National Congress has lost the moral compass he bequeathed it when he stepped down as president in 1999. Mr Mandela spent much of last year in Qunu, his ancestral village in the Eastern Cape province. But since his release from hospital in December he has been at his home in Johannesburg, closer to medical facilities.