US President Barack Obama on Friday said that Nelson Mandela was a "hero for the world" whose legacy will live on throughout the ages, as the anti-apartheid hero lay critically ill in hospital.
"He is a personal hero. I think he is a hero for the world, and if and when he passes from this place, one thing I think we all know is that his legacy is one that will linger on throughout the ages," Obama said in Senegal.
Mandela was on Thursday on life support in a Pretoria hospital and his condition was casting doubt over Obama's visit to South Africa, due to begin on Friday.
But Obama, who said Mandela had inspired him to become involved in politics, said he still planned to travel to South Africa, and said the prayers of the American people were with the South African ex-president's family.
Obama, using Mandela's clan name "Madiba", said Mandela had given him a "sense of what is possible in the world, when righteous people of goodwill work together".