Former South African President Nelson Mandela is "doing very, very well" in a Pretoria hospital, but will remain for further tests for an undisclosed condition.

The 94-year-old Nobel Peace Prize winner was airlifted to the hospital and admitted on Saturday, The Telegraph reports.

Mandela was imprisoned for 27 years by the apartheid government of South Africa, and then led the struggle against apartheid. In 1994 he became the country's first black president.

On Sunday, South African President Jacob Zuma visited Mandela. Zuma's spokesman told the BBC that Mandela "is in the hands of a competent medical team," but would not provide additional details.

Zuma said Mandela's medical issue is "consistent with his age," CNN reports.

"[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," said Maharaj.

Mandela was hospitalized in February for abdominal pain and underwent a procedure. In January 2011 he was treated for a chest infection.

The BBC reports:

[T]here 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 center of protests and funerals during apartheid.

"Yes, it really worries us because he is a great person," churchgoer Shainet Mnkomo told the Associated Press. "He did so many things to the country, he's one of those persons who we remember most."

A statement on Zuma's website noted:

Today is also a special day as President Mandela received the Nobel Peace Prize on the 10th of December 1993, International Human Rights Day for his selfless contribution to the struggle for liberation, human rights and justice in South Africa.

Reuters offered this video on Monday: