South Africa's President Jacob Zuma on Saturday visited former president Nelson Mandela as he marked two weeks of being at a Pretoria hospital. "President Zuma this morning visited former President Mandela in hospital in Pretoria. Zuma assured him of the love and support of all South Africans, young and old, and the whole world," said the Presidency on Saturday.

Mandela was admitted at the hospital on Dec. 8 for recurrent lung infection, and some gall stones were removed from him after an operation.

The 94-year-old Mandela was said to be responding well to treatment, and doctors were keeping him in hospital as a precaution measure to monitor his improvement.

In a statement President Zuma said on Saturday, "We urge South Africans to continue praying for our beloved Madiba (the nickname of Mandela) during this period. Our hearts are with his whole family and relatives."

It was reported that Mandela's current stay in hospital is his longest since he was freed over two decades ago.

This was the second time for President Zuma to visit Mandela since his admission. Various government officials have visited him in recent days.

Mandela spent 27 years in prison for the movement of the national liberation, and became the first democratically-elected president of South Africa in 1994 as the apartheid ended.

He has a history of lung problems having suffered from the tuberculosis towards the end of the 27 years in prison.