JOHANNESBURG -- Former President Nelson Mandela of South Africa was readmitted to the hospital overnight because of a recurring lung infection, President Jacob Zuma said in a statement on Thursday, appealing to people around the world to pray for Mr. Mandela.
It was the third time in four months that Mr. Mandela, 94, South Africa's first black president and former leader of the dominant African National Congress, had been hospitalized. He was admitted shortly before midnight on Wednesday, the statement said, but the authorities delayed the announcement for several hours. The episode rekindled worries about his frailty.
Mr. Mandela spent 19 days in December hospitalized for a lung infection and what government officials described as the surgical removal of gallstones. He was readmitted earlier this month for what was termed a scheduled checkup.
Mr. Mandela has struggled with lung problems since he contracted tuberculosis during his 27 years in prison in the apartheid era, when his incarceration became a potent symbol in South Africa and around the world of the struggle to throw off a codified system of racial domination devised by the country's white rulers.
Mr. Mandela led the A.N.C. through the negotiations that led to the first fully democratic elections in 1994 and the end of white minority rule. His name still resonates as an emblem of his effort to transcend decades of racial division and create what South Africans called a rainbow nation.
"We appeal to the people of South Africa and the world to pray for our beloved Madiba and his family and to keep them in their thoughts," Mr. Zuma's statement said, referring to Mr. Mandela by his clan name. "We have full confidence in the medical team and know that they will do everything possible to ensure recovery."
Later on Thursday, the president's office issued another statement saying that Mr. Mandela's doctors said he was "responding positively to the treatment he is undergoing."
Mr. Zuma then tried to dissipate the sense of alarm. "Let us slow down the anxiety," he told the BBC. "The country must not panic; Madiba is fine."
Mr. Mandela retired from public life in 2004 and was last seen publicly in 2010, when he briefly appeared at the World Cup soccer tournament, which South Africa hosted. But he receives frequent visits from old friends. When Mr. Mandela was discharged from the hospital in December, Mac Maharaj, a spokesman for Mr. Zuma, said Mr. Mandela would be staying at home in a suburb of Johannesburg and receiving high-level care there.
His recurrent bouts of illness added to a sense of foreboding after a year in which South Africa has faced perhaps the most serious unease and unrest since the end of apartheid provoked by a leadership struggle within the A.N.C. and a wave of wildcat strikes by angry mine workers.
Additionally, President Zuma has come under public scrutiny in recent months, particularly in relation to how $27 million of government money was spent on upgrades to a private homestead and compound in rural Zululand. The looming questions highlight a broader perception that Mr. Mandela's near saintly legacy from the years of struggle has been eroded by a more recent scramble for self-enrichment among a newer elite.
Alan Cowell contributed reporting from London.world
This article originally appeared in The New York Times.