JOHANNESBURG -- South Africa's ruling party called for calm Thursday after former president Nelson Mandela was admitted to the hospital for what his foundation described as "routine tests."
"We call on all South Africans to remain calm regarding the hospitalization ... and not press any panic buttons, as there is no reason for that whatsoever," African National Congress spokesman Jackson Mthembu said. "If there are any developments, the Mandela Foundation and the family of Mandela will be able to tell all of us."
The foundation said Wednesday that the 92-year-old Nobel Peace Prize winner was in Milpark Hospital in Johannesburg for routine tests but that his health was not in jeopardy.
"He is in no danger and is in good spirits," said a statement from the foundation, which Mandela established to continue his charitable work after withdrawing from public life in 2004.
The Star newspaper reported Thursday that Mandela was seen by a lung specialist. "He has been admitted for investigation," the doctor, Michael Plit, told the newspaper. He declined to comment on Mandela's condition.
Mandela's wife Graca Machel and other family members were seen at the hospital Wednesday night, and Machel's daughter Josina and Mandela's personal assistant Zelda la Grange were at the hospital Thursday morning.
The news put South Africa on edge over the health of the increasingly frail "Madiba" -- the clan name by which Mandela is affectionately known.
Media flocked to the hospital for news on Mandela's health, but a tight security presence surrounded the building, with police checking all visitors' cars to make sure no journalists were hiding inside.
At a school next door to the hospital, children decorated a fence with colourful pictures of hands and hearts and messages of support.
"We hope you'll get well soon," said one.
"Madiba, we love you," said a sign in one of the school's windows.
Mandela's public appearances have become increasingly rare since his retirement. His last public outing was at the closing ceremony of the 2010 FIFA World Cup in Johannesburg.