"I cannot comment on the clinical details of these reports because that would breach the confidentiality of the doctor/patient relationship," Maharaj told South Africa's Radio 702.

During his visit Wednesday evening, Zuma was told by doctors that they “are still doing everything they can to ensure (Mandela’s) well-being,” read a statement from Zuma’s office.

Zuma was to travel to Maputo, the capital of Mozambique, on Thursday for a meeting about regional investment.

Other visitors to Mandela’s bedside Wednesday included his former wife, Winnie Madikizela-Mandela. The couple divorced in 1996.

U.S. President Barak Obama began a weeklong trip in Africa on Wednesday, landing in the Senegalese capital of Dakar.

The president, who is travelling with first lady Michelle Obama and daughters Malia and Sasha, is also scheduled to visit South Africa and Tanzania.

Meanwhile, South Africans continue to pay tribute to the anti-apartheid icon, leaving flowers and cards outside the hospital and his home in Johannesburg. On Wednesday, children from a daycare laid a handmade card outside the hospital and paused to recite a poem.

The Zulu poem included the line, “Hold on, old man,” according to the South African Press Association.

Politicians, celebrities and world leaders have also reached out to express admiration and concern for Mandela, who has long been admired for his message of hope and forgiveness despite 27 years of imprisonment by South Africa’s apartheid government. He was elected as South Africa’s first black president in 1994 as the country ushered in a new era of democracy.

In the Eastern Cape province, where Mandela grew up, tribal leader Phathekile Holomisa said he has spoken to Mandela’s family members, who are holding out hope that he will pull through but understand that there may be little left for doctors to do.

"I am of the view that if Madiba is no longer enjoying life, and is on life support systems, and is not appreciating what is happening around him, I think the good Lord should take the decision to put him out of his suffering," Holomisa said.

The Anglican archbishop of Cape Town, Thabo Makgoba, visited Mandela in hospital on Tuesday, and said a prayer for a “peaceful, perfect end” for the former president.

Makgoba told The Associated Press that: "We just want him to be peacefully released, whatever he's feeling at this moment, and to be reunited with his Maker at the perfect time, when God so wills."

Mandela, whose 95th birthday is on July 18, served a single five-year term as president. He later turned his attention to charity.

Mandela withdrew from public life years ago and has become increasingly frail in recent years.

His last public appearance was at the 2010 World Cup, which was hosted by South Africa.

With files from The Associated Press