Nelson Mandela's granddaughter has told reporters outside the hospital where he's being treated that her grandfather is stable.

The former South African President was put on life support last night at a Pretoria Hospital.

Crowds of people are continuing to hold vigils outside, as they prepare to say farewell to the anti-apartheid leader.

Zuma cancels trip

Meanwhile, South African President Jacob Zuma has cancelled a trip to an economic conference in Mozambique after visiting Mandela, who tribal elders say is on life support.

President Zuma arrived at the clinic in Pretoria late last night. He only stayed about 10 minutes, during which time he was briefed, but felt then that he had to go and cancel his appearance at an economic conference in Maputo, Mozambique.

An update is expected on his condition at midday. 

Pictured above, a child outside the Pretoria clinic where Mandela is being treated