The Presidency said Mr Mandela had been ill for several days at his Johannesburg home.
"During the past few days former President Nelson Mandela has had a recurrence of lung infection," statement released on Saturday said. "This morning at about 1.30am his condition deteriorated and he was transferred to a Pretoria hospital. He remains in a serious but stable condition."
Presidential spokesman Mac Maharaj told Britain's Sunday Times that doctors told him "be concerned, but don't be hysterical".
"I questioned the doctors ... They said: 'Look, yes, he is able to breathe on his own. Be concerned, but don't be hysterical about it. Also don't tell the public that he is getting better [for now]'."
North West Premier Thandi Modise on Monday wished Mr Mandela a speedy recovery.
"To many across the globe, in our country and province, Tata Madiba is a unifier and a symbol of reconciliation. Though we know that he is not immortal like all of us, we are inspired by his fighting spirit and wish his family all the strength for them to unite in love and continue to give him all the support he needs. We are confident that he is receiving the best medical care and treatment that the best of our facilities and medical specialists have to offer," said Modise.
"Though we should appreciate that there are a few people the world over who match Madiba's stature as the greatest freedom fighter and statesman the world has known, the zeal to keep the public informed about his condition should not erode his dignity."
Prayers have been said in churches across the country.
Image: © Getty
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