South Africa's first black President Nelson Mandela has a lung infection but is responding to treatment, South African government said Tuesday, as the revered anti-apartheid icon spent his fourth day in hospital.
This is the first time officials have revealed why Mr Mandela, 94, was rushed to a military hospital in the capital, Pretoria, on Saturday.
Tests showed a "recurrence of a previous lung infection", presidential spokesman Mac Maharaj said.
Mr Mandela is responding to his treatment, Mr Maharaj added.
News of the hospital stay has prompted much concern in South Africa.
He was last admitted to hospital in February when he was treated for abdominal pain.
In January 2011, he was treated for a serious chest infection.