The announcement was made as the former president celebrated his 95th birthday in hospital amid tributes from around the country and the world.
The Nobel Peace Prize laureate, globally admired as a symbol of struggle against injustice and of racial reconciliation, has been under treatment since June 8 for a recurring lung infection that has led to four hospital stays in the past six months.
“Madiba remains in hospital in Pretoria, but his doctors have confirmed that his health is steadily improving,” President Jacob Zuma’s office said in a statement, using Mandela’s traditional clan name.
“On behalf of government and all the people of South Africa, we wish Madiba a joyous 95th birthday.”
In celebrations across the country, schoolchildren and admirers gathered to sing “Happy Birthday” to Mandela.
He was elected South Africa’s first black president in 1994 when the country’s first multiracial elections put an end to the apartheid system. Four years earlier, he was released from 27 years spent in prison under white minority rule.
In 2009, the United Nations declared July 18 as Nelson Mandela International Day. This is commemorated in South Africa and abroad with 67 minutes of charitable acts to mark the 67 years that Mandela actively fought for an end to apartheid.
Mandela, described by his doctors as being in a critical but stable condition in recent weeks, is expected to spend his birthday in hospital with visits from his close family.
His faltering health has reinforced a realisation among South Africans that the father of their post-apartheid ‘rainbow nation’ will not be around for ever.
Mandela’s former wife Winnie said on Thursday his birthday was a “gift to the nation” and she urged South Africans to celebrate the day with acts of kindness to others.