South Africa's former president Nelson Mandela is being treated for a lung infection.
The statement from the president's office is the first time officials have revealed why the 94-year-old was rushed to a military hospital in the capital, Pretoria, at the weekend.
A spokesperson says tests showed a recurrence of a previous lung infection and Mr Mandela is responding to treatment.
He was flown to hospital on Saturday from his home in Qunu village in Eastern Cape province by the military, which is responsible for his healthcare, the BBC reports.
Mr Mandela was South Africa's first black president and is regarded by most South Africans as the father of the nation. He was awarded the Nobel Peace Prize in 1993.