Nelson Mandela remains in a critical condition in hospital, South African president Jacob Zuma said, stressing doctors were doing their best to make the anti-apartheid hero comfortable.
"Former president Mandela remains in a critical condition in hospital. The doctors are doing everything possible to ensure his well being and comfort," Zuma said.
Zuma reported that the 94-year-old's health had deteriorated over the weekend, after he visited the icon's bedside late Sunday.
"Given the hour that we got to the hospital it was late, he was already asleep," Zuma said.
"(We) saw him and then we had a bit of discussion with the doctors and his wife Graca Machel."
Zuma declined to give details about the health of his predecessor, who was rushed to hospital 17 days ago with a recurring lung infection.
"I don't think I'm in a position to give further details, I am not a doctor. That is what I informed the country and the world and that remains the case for now," Zuma said.
In Washington, the White House said its thoughts and prayers were with Mandela, as US President Barack Obama prepares to visit South Africa.
"We have seen the latest reports from the South African government that former president Mandela is in critical condition," National Security Council spokeswoman Caitlin Hayden said.
"Our thoughts and prayers are with him, his family and the people of South Africa."
Obama leaves Wednesday on a tour of Africa that will take him to Senegal, South Africa and Tanzania.
The possibility of a meeting between the first black presidents of both South Africa and the United States has been hotly anticipated for years. The White House has said it will defer to Mandela's family regarding any meeting.
As much as Mandela is loved by South Africans, with the latest hospitalisations many have come to terms with their hero's fragility.
"It is not up to us to decide what happens now. There is nothing we can do," said Aphiwe Ngesi a teacher in Mthatha.
"All we can do is hope for the best."
Many South Africans have instead begun to look anew at his achievements
During 27 years in jail he became the figurehead of the anti-apartheid movement. On his release he negotiated an end to white rule and won the country's first fully democratic elections.
As president he guided the country away from internecine racial and tribal violence.
It was 18 years ago today that, in a deeply symbolic moment, he handed the rugby world cup to a victorious Springboks captain Francois Pienaar.
The impact of a black president appearing at this most white of South African sports still reverberates today.
"Mandela soared above the petty confines of party politics," said political commentator Daniel Silke.
Sunday's announcement came after unconfirmed media reports that Mandela's condition was worse than what authorities and relatives had suggested.
Mandela's daughter Makaziwe Mandela rubbished those claims telling CNN earlier Sunday that "he still opens his eyes, ...the touch is there."
The South African government has also been criticised amid revelations that the military ambulance that carried Mandela to hospital developed engine trouble, resulting in a 40-minute delay until a replacement ambulance arrived.
The presidency said that Mandela suffered no harm during the wait for another ambulance to take him from his Johannesburg home to a specialist heart clinic in Pretoria 55 kilometres (30 miles) away.
"There were seven doctors in the convoy who were in full control of the situation throughout the period. He had expert medical care," said Zuma.
The doctors also dismissed the media reports that Madiba suffered cardiac arrest (the day he was taken to hospital). "There is no truth at all in that report," said Zuma.
News about the icon's health made headlines in most local newspapers: "World on edge as Mandela's condition worsens" said Business Day.
