President Jacob Zuma visited the 94-year-old, according to an official statement. It provided no other details of the health of South Africa's first black president, who came to power after historic all-race elections in 1994.
On Saturday, Zuma's office said there was no cause for alarm and that the medical treatment Mandela was receiving in the military hospital in the capital was "consistent with his age".
However, domestic media reports suggested that senior members of the government and people close to Mandela had been caught unawares by his admission to hospital.
The City Press newspaper said both the Nelson Mandela Foundation and his ex-wife, Winnie Madikizela-Mandela, had not known about his transfer to the capital from his home in the remote village of Qunu in the Eastern Cape province.
South Africa's Sunday Times said deputy President Kgalema Motlanthe had cancelled a scheduled visit on Friday to Mandela in Qunu after being told of his condition.
The mood around Pretoria's Military One hospital was calm on Sunday. Army personnel were searching all cars driving onto the premises.
Mandela is a hero to many South Africans and two brief stretches in hospital in the last two years have made front page news.
"I wish Mr Mandela a quick recovery from his sickness so we can be with him all the time. He was a good president, a good leader, so he must be with us," said John Sekiti, a petrol station attendant in Pretoria.
Mandela was admitted to a Johannesburg hospital in 2011 with a respiratory condition, and again in February this year because of abdominal pains. He was released the following day after a keyhole examination showed there was nothing serious.
He has since spent most of his time in Qunu.
His frail health prevents him from making any public appearances in South Africa, although he has continued to receive high-profile domestic and international visitors including former US President Bill Clinton.