This comes after the 94-year-old anti-apartheid hero was taken to hospital for the third time in four months for a lung infection.
The medical report was a relief to South Africans who had been anxiously praying and waiting for an update on the health of the Nobel Peace Prize laureate, hospitalised before midnight on Wednesday. Global leaders sent their best wishes.
The ANC had already reported Mandela was responding well to treatment, and President Jacob Zuma had sought to reassure the nation, recalling that the revered statesman's advanced age meant he required frequent medical checks.
"President Nelson Mandela is in good spirits and enjoyed a full breakfast this morning," Zuma's office said in a statement. "The doctors report that he is making steady progress. He remains under treatment and observation in hospital," it added.
Mandela became South Africa's first black president after winning the country's first all-race election in 1994. A former lawyer, he is revered at home and abroad for leading the struggle against white minority rule – including spending 27 years in prison on Robben Island – and then promoting the cause of racial reconciliation. In churches across South Africa, many included Mandela in their prayers on Good Friday, one of the most important days in the Christian calendar.
At the Regina Mundi Catholic Church in the Soweto township outside Johannesburg where Mandela once lived, churchgoers lit candles for him. "He's an icon today and we are free because of him," parishioner Oupa Radebe said. "I hope this time God will have mercy on him to give him the strength and courage to continue to be an icon for our country," Father Benedict Mahlangu said at the service. US President Barak Obama sent Mandela his best wishes.
"When you think of a single individual that embodies the kind of leadership qualities that I think we all aspire to, the first name that comes up is Nelson Mandela. And so we wish him all the very best," he said.
'Like a father'
Mandela's fragile health has been a concern for years as he has withdrawn from the public eye and mostly stayed at his affluent homes in Johannesburg and in Qunu, the rural village in the destitute Eastern Cape province near where he was born. President Zuma has urged the nation to remain calm.
"Of course I have been saying to people, you should bear in mind Madiba is no longer that young and if he goes for check-ups every now and again, I don't think people must be alarmed about it," Zuma told the BBC on Thursday. "In Zulu, when someone passes away who is very old, people say he or she has 'gone home'. I think those are some of the things we should be thinking about."
Madiba is the clan name by which many South Africans refer to Mandela, whose face adorns the country's new bank notes. Despite his absence from the political scene for the past decade, he remains an enduring and beloved symbol of the struggle against racism.
"He's like a father to me … There is no more apartheid, black and white can go to the same places," said Princess Nopuhle, a student, aged 18, in Johannesburg's Mandela Square. As he has receded from public life, critics say his ruling African National Congress (ANC) has lost the moral compass he bequeathed it when he stepped down as president in 1999.
Under such leaders as Mandela, Walter Sisulu and Oliver Tambo, the ANC gained wide international respect when it battled white rule.
Leader of 'Golden Period'
Once the yoke of apartheid was thrown off in 1994, it began governing South Africa in a blaze of goodwill from world leaders who viewed it as a beacon for a troubled continent and world.
Almost two decades later, this image has dimmed as ANC leaders have been accused of indulging in the spoils of office, squandering mineral resources and engaging in power struggles.
Mandela has been criticised for not doing enough to prevent an HIV/AIDS epidemic and for making political compromises in the transition from apartheid that led to the black majority being still largely excluded from the benefits of the country's mineral wealth. But his achievement in leading South Africa out of apartheid and averting all-out racial war is seen as eclipsing this.
"Amongst most South Africans, he is associated with a so-called 'golden period' of the end of apartheid and the beginning of the new democratic state. He represents all of the best of that, including the reconciliation," said Nic Borain, an independent political analyst.
Mandela was in hospital briefly earlier this month for a check-up and spent nearly three weeks in hospital in December with a lung infection and after surgery to remove gallstones.
That was his longest stay in hospital since his release from prison in 1990 after serving almost three decades for conspiring to overthrow the apartheid government. Mandela has a history of lung problems dating back to when he contracted tuberculosis as a political prisoner.
Many South Africans said they felt the country's problems had worsened since Mandela withdrew from active politics.
"There was more peace and freedom when he was running it. Now the splits have come back again," said Natascha Roberts, taking pictures of her family in front of a towering statue of Mandela at the Sandton City mall in suburban Johannesburg. "If he can go on for another few years, it would be great." – Reuters