Former South African President Nelson Mandela is said to be "doing well" after spending a second night in the Pretoria hospital where he was admitted on Saturday.
Presidential spokesman Mac Maharaj said Mr Mandela, 94, was "comfortable" and there was "no cause for alarm".
On Sunday Mr Mandela was visited by President Jacob Zuma, who said he was looking well after a restful night.
News of the hospital stay has prompted much concern around South Africa.
Mr Zuma has been reassured that Mr Mandela - admitted to hospital on Saturday to undergo tests - is in the hands of a competent medical team, Mr Maharaj told the BBC, without giving further details about his treatment or condition.
"[We want to] avoid news about Madiba's [Mr Mandela's clan name] health being treated as if it is the movement of share prices on the stockmarket," Mr Maharaj added.
Mr Mandela was taken from his home in the rural village of Qunu, in Eastern Cape province, to hospital in the capital on Saturday. Local media report that the decision to move him was taken so quickly that some family members and his own foundation were initially unaware of it.
Mr Zuma's office said on Saturday that Mr Mandela needs medical attention "from time to time which is consistent with his age".
The authorities are keen to respect Mr Mandela's privacy and control any information about his health, the BBC's Andrew Harding in Johannesburg reports.But there is enormous public concern here for the man widely revered as the father of democratic South Africa, he adds.
Prayers were held for the former leader at the Regina Mundi Catholic church in the Soweto area of Johannesburg, once the centre of protests and funerals during apartheid.
"Yes, it really worries us because he is a great person," churchgoer Shainet Mnkomo told Associated Press. "He did so many things to the country, he's one of those persons who we remember most."
The Congress of South African Trade Unions said it hoped the government's statement about his condition was true, and urged Mr Mandela to: "Get well and continue to inspire us".Good spiritsMr Mandela retired from public life in 2004 and has been rarely seen in public since.
He served as South Africa's first black president between 1994 and 1999, and received the Nobel Peace Prize in 1993.
He spent more than two decades in jail for leading the struggle against South Africa's white minority apartheid regime.
Mr Mandela was last in hospital in February, when he underwent a minor procedure to investigate the causes of an abdominal problem.
And in January 2011 he was treated for a serious chest infection.
Mr Mandela spends the majority of his time in Qunu, which is close to where he was born.
Our correspondent says he is known to be frail and his memory is fading, but visitors have repeatedly said he is in good spirits.