Updated

Anti-apartheid icon Nelson Mandela is improving in hospital as he fights a recurrent lung infection and is not 'going to die tomorrow,' former South African president Thabo Mbeki has said.

The 94-year-old who became South Africa's first black president was Friday spending his 14th day in hospital where he has been listed in serious condition.

Mbeki said on local PowerFM radio that he is in contact with the family and medical staff of the man he succeeded in 1999.

"Naturally ...I maintain very close contact with the family and the doctors about Nelson Mandela's condition," he told the radio late Thursday.

"And I think that we need to understand what has been said publicly by government, which is that Nelson Mandela is in fact improving in terms of his health.

"I don't think that anybody should kind of entertain some wrong notion, that Nelson Mandela is going to die tomorrow, he is not going to."

Mandela's latest hospitalisation, the fourth in seven months, has been met with a sense of resignation among many South Africans, who have come to terms with their icon's mortality.

On Thursday the Pretoria hospital treating Mandela received 20,000 litres in emergency water deliveries after a planned maintenance water cut lasted longer than expected, radio 702 reported.

The maintenance started on Tuesday and was due to end on Wednesday, but was prolonged because a problem arose as technicians tried to switch back supplies.

The water supplies were restored early Friday, the municipality of Pretoria said.

Mandela, who was rushed to a Pretoria hospital on June 8 with a recurrent lung infection, is due to celebrate his 95th birthday on July 18.

On Monday one of his daughters, Zenani Mandela-Dlamini who is South Africa's ambassador to Argentina, told reporters gathered outside the hospital that the Nobel peace laureate was doing "very well."

The previous day South African President Jacob Zuma said that Mandela was showing a "sustained" improvement after more than a week in hospital although his condition remained serious.

Mandela is admired throughout the world for his lifelong sacrifice in fighting the brutal regime of racial segregation installed with apartheid in 1948, and for his role in bringing multiracial democracy to South Africa, a country many feared would disintegrate into civil war.