The condition of the 95-year-old Mandela remains critical but stable and he continues to respond to treatment, Xinhua cited the presidency as saying.
"We appreciate that he (Mandela) has been in hospital for 50 days already, but we must take solace that he is being attended to by the most formidable and competent medical teams that we could put together, so he is under good care," presidential spokesperson Mac Maharaj told the South African Broadcasting Corporation.
"He is responsive and we should take heart from that," Maharaj said.
Mandela was rushed to a hospital in Pretoria June 8. This is his fourth and longest hospital stay since December last year.
The Nobel Peace Prize laureate has been suffering from a lung infection, the result of tuberculosis developed when he was imprisoned during the apartheid.
South African President Jacob Zuma visited Mandela a few days ago and assured the former president of "love and support of all South Africans".
Mandela turned 95 July 18.