The Nelson Mandela Foundation, The Nelson Mandela Children's Fund and the Mandela Rhodes Foundation said on Friday further arrangements would be announced regarding Mandela's funeral.
"We want to express our sadness at this time. No words can adequately describe this enormous loss to our nation and to the world.
"We give thanks for his life, his leadership, his devotion to humanity and humanitarian causes. We salute our friend, colleague and comrade and thank him for his sacrifices for our freedom. The three charitable organisations that he created dedicate ourselves to continue promoting his extraordinary legacy.
"Hamba Kahle Madiba," the three foundations said.
Former president Thabo Mbeki said Mandela's death represented a "very sad moment" of grief for he and his wife, Zanele, as well as their family.
"But it also constitutes a personal loss for us because over many decades, he served both as our guide and one of our fathers.
"President Mandela, Madiba, and his generation of freedom fighters walked their long walk and made enormous sacrifices which eventually led to our freedom in 1994. His passing signals the end of an historic era represented by the heroic deeds of his generation."
Mbeki said Mandela's passing represented an opportunity to "commit ourselves selflessly to address the many "challenges we face".
"President Mandela and his generation discovered the mission of their generation. They were at all times faithful to it, as a result of which they fulfilled it. As we mourn president Mandela's passing we must ask ourselves the fundamental question – what shall we do to respond to the tasks of building a democratic, non-racial, non-sexist and prosperous South Africa, a people centred society free of hunger, poverty, disease and inequality, as well as Africa's renaissance, to whose attainment president Nelson Mandela dedicated his whole life?"