Former South African leader Nelson Mandela is responding to treatment for a lung infection that has reoccurred.

In a statement Tuesday, a spokesman for President Jacob Zuma also said doctors have concluded tests on Mr. Mandela that revealed the infection.

The 94-year-old former president was admitted to a Pretoria hospital Saturday for what government officials said were tests “consistent with his age.” He has grown frail and has not made a public appearance in several years.

Mr. Mandela was admitted to a Johannesburg hospital in January, 2011 for an acute respiratory infection. He also tested positive for tuberculosis in 1988, during his 27-year imprisonment for fighting minority white rule.

He became South Africa's first black president in 1994.