Nelson Mandela was admitted to hospital in Pretoria on Saturday morning after his condition deteriorated with a lung infection, South African President Jacob Zuma’s office said.

The 94-year-old anti-apartheid revolutionary leader is in a “serious but stable condition,” the presidential office said.

The former President is "receiving expert medical care and doctors are doing everything possible to make him better and comfortable,” the statement said.

Expressing the views of the African National Congress, National Spokesman Jackson Mthembu said the party and supporters were praying for the former president and his family. "We send to him our well wishes for a speedy recovery so that he may soon be discharged to return to the care and comfort of his home," Mthembu was quoted as saying by the Telegraph.

Mandela became South Africa’s first black president in 1994, after spending decades in prison fighting against racial segregation in the country by the white regime.

His 27 years of prison life, which involved working in a quarry, is believed to have inflicted damage to his lungs.

He was last seen in late April and appeared frail and detached in a video shot at his Johannesburg home.

On April 6, he was released after a 10-day treatment for pneumonia.

Last December, he was hospitalized for 18 days for a lung infection treatment and surgery to remove gall bladder stones.

In early April, a South African satellite network accidentally broadcast an obituary of Mandela, called “Remembering Madiba 1918-2013.”

The clip was aired multiple times before DSTV, run by Universal Networks, a division of NBCUniversal, realized the error.

Universal Networks, which came under criticism for showing disrespect toward Mandela’s family, apologized for the “alarm and offense caused by the error.”

Mandela was awarded the Nobel Peace Prize in 1993, along with the former South African President F.W. de Klerk. Mandela retired from public life in 2004 and ever since has rarely been making public appearances.