The 94-year-old former South African president was comfortable and continuing to respond to treatment, the statement said, adding that Mandela had developed a pleural effusion - excess fluid in the lungs which had been drained to enable him to breathe more easily, BBC reported.
The statement read by presidential spokesperson, Mac Maharaj, said: "Doctors advised that due to the lung infection, former president Mandela had developed a pleural effusion which was tapped. This has resulted in him now being able to breathe without difficulty.
"He continues to respond to treatment and is comfortable."
The presidency "would like to acknowledge and thank all who have been praying for, and sending messages of support for, Madiba and his family", it added.
After Madiba, as Mandela is popularly called in the country, was hospitalised late Wednesday, President Jacob Zuma had appealed to people they "must not panic".
This latest spell in hospital is Mandela's fourth in just over two years.
The former president first contracted tuberculosis in the 1980s while detained on windswept Robben Island during national struggle. His lungs are said to have been damaged while working in a prison quarry.
Regarded by many as the father of the nation for leading the struggle against apartheid, Mandela served as South Africa's first black president from 1994 to 1999.