Nelson Mandela, the former president of South Africa, is in “serious but stable condition” after contracting a lung infection, South Africa officials said.

The 94-year-old Nobel Peace prize winner’s “condition deteriorated and he was transferred to a Pretoria hospital,” early Saturday morning according to statement from the office of South African President Jacob Zuma.

“The former President is receiving expert medical care and doctors are doing everything possible to make him better and comfortable,” the statement said. “President Jacob Zuma, on behalf of government and the nation, wishes Madiba a speedy recovery and requests the media and the public to respect the privacy of Madiba and his family.”

In April, Mandela spent 18 days in the hospital due to a lung infection and was treated for gall stones in December 2012.