Mandela is responding well to treatment

Former president Nelson Mandela has steadily improved after having been hospitalized for more than 10 days, President Jacob Zuma said on Thursday.

Mandela's health condition is "serious" but he is "responding well to treatment" after suffering a lung infection and undergoing surgery for gallstones, Zuma told delegates attending the 53rd elective conference of the African National Congress (ANC).

Mandela 94, who has been an "unparalleled fighter and always been so," has met all his health challenges with "tremendous fortitude and grace," Zuma said.

Mandela has been hospitalized in a Pretoria hospital since Dec. 8 for a lung infection and gallstones.

He underwent a successful surgery to have the gallstones removed last week after doctors attended to his lung infection.

Mandela's health has been a focus of concern. His hospital stay this time is his longest since 2001, when he underwent seven weeks of radiotherapy after being diagnosed with prostate cancer.

Mandela, who was imprisoned for 27 years during apartheid, was elected the country's first black president in 1994.