Mr Mandela has been in hospital since 8 June
Reports that former South African President Nelson Mandela has been discharged from hospital are incorrect, South Africa's presidency says.
The BBC and other news outlets earlier quoted sources close to Mr Mandela as saying he had returned home.
The presidency said in a statement that Mr Mandela was critical but stable, but at times his condition became unstable, prompting medical intervention.
The 95-year-old was admitted with a recurring lung infection on 8 June.
The country's first black president, Mr Mandela is revered by many as the father of the nation.
His prolonged hospital stay - by far the longest since he was released from prison in 1990 - has caused concern both in South Africa and abroad.
The BBC's Mike Wooldridge in Johannesburg says the family has long hoped that he would improve sufficiently at least to enable him to make the journey home in the Johannesburg suburb of Houghton and be treated there.
But one of the sources quoted by international media has now spoken of being misinformed about Mr Mandela's release.
The confusion could have arisen out of a possible move soon to get the former president home, which would clearly depend on his health at the time, our correspondent says.
The infection he is being treated for is said to date back to a period of nearly three decades he spent in prison for anti-apartheid activity.
People from South Africa and around the world have sent him their best wishes, and flowers and other tributes have collected outside Pretoria's MediClinic Heart Hospital.
Throughout Mr Mandela's stay in hospital, President Jacob Zuma has urged the country to pray for him and keep him in their thoughts.