South African President Jacob Zuma has visited Nelson Mandela in hospital and says he "looks well after a restful night", Mr Zuma's spokesperson said.
The president has been reassured that Mr Mandela is in the hands of a competent medical team at the hospital in Pretoria, Mac Maharaj told the BBC.
The 94-year-old was admitted to hospital on Saturday to undergo tests.
South Africans have been waiting for word on Mr Mandela's condition amid messages of hope for a speedy recovery.
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.
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"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."
- BBC