Zuma received Obama and his delegation at the Union Buildings, the country's seat of government, on the first morning of his three-day visit to the country.

The US president arrived late on Friday from Senegal, where he began his Africa tour. He is accompanied by his wife, First Lady Michelle Obama, and their daughters, Malia and Sasha.

The White House confirmed that the Obamas would meet privately late Saturday with relatives of former South African President Nelson Mandela. The statement added that Barack Obama would not be meeting the critically ill anti-apartheid leader in hospital.

"The President and First Lady will meet privately with members of the Mandela family to offer their thoughts and prayers at this difficult time," a US official said.

"Out of deference to Nelson Mandela's peace and comfort and the family's wishes, they will not be visiting the hospital," the unnamed official told the news agency AFP.

Mandela, a Nobel Peace Prize winner, is critically ill with a recurrent lung disease dating from his time in apartheid-era prisons, where he was incarcerated for 27-years for his struggle under white-minority rule.

Later on Saturday, the US president is set to meet with young people in Soweto, the scene of the 1976 student protests against the racist apartheid regime while Mandela and fellow African National Congress leaders were incarcerated.

Obama's three-country tour concludes next week in Tanzania.

jlw/mkg (AP, AFP, dpa)