By Henri du Plessis and John Yeld
Dr Anton Rupert, a giant of South African commerce and industry and reputedly one of the richest men on earth, died at his home in Stellenbosch early today.
He was 89.
Rupert is said to have died peacefully in his sleep.
The tycoon and philanthropist was a friend of world leaders, a leading patron of the arts and education, and an avid nature lover.
He had been battling age-related ill health and was said to have been lonely since the death of his wife, Huberte, in 2005.
"The exact cause of his death has not been established, but Dr Rupert has been struggling with his health over the past three or so years," family spokesperson Hans Knoetze said on Thursday.
Nelson Mandela was among the first to express his sorrow at the death of a man he described as a close friend.
Zelda la Grange, Mandela's spokesperson, said: "Mr Mandela and Dr Rupert were very close friends. Mr Mandela believes we have lost a giant South African."
Mandela had admired Rupert not only as a person, but also for his contribution to South Africa, she said.
Mandela would contact Rupert's son, Johann, later on Thursday to express his condolences.
President Thabo Mbeki said Rupert had not only distinguished himself in the Afrikaner community, but also played a significant role in supporting and initiating the transformation of South African business.
"Not only will he be remembered for his business acumen, but also for his total devotion to nature and environmental conservation as shown by his immense contribution to the establishment of numerous transfrontier parks. A true philanthropist."
Tony Leon, leader of the DA, described Rupert as the "ultimate renaissance man".
"I think he really was a builder and architect of the South African economy, of wildlife conservation and the arts.
"He had a deep wisdom, and understanding of the people and soil of this land."
The ANC said it was saddened by Rupert's death.
"South African has lost one of its most prominent businessmen.
"Rupert had made a significant contribution to South Africa, but also to broader social causes. He was a pioneer, in business as well as in the field of conservation."
Environment Minister Marthinus van Schalkwyk said he had learned of Rupert's death "with great sadness".
"His passing marks the end of an era in global conservation."
In a special tribute issued by the family today, Rupert was described as a "mixture of ideas and action - a man who tackled the challenges of the future with the wisdom and experience of the past.
"He always kept his eyes on the entire world, without losing sight of his own people. For them, he always made time," the family said.
Rupert began as the owner of a small Pretoria drycleaners. But his formidable entrepreneurial skills built an empire that spanned the tobacco, mining and wine industries.
He was born on October 4, 1916, in Graaff-Reinet, and completed his schooling there, before obtaining a B Sc and M Sc in applied chemistry at the University of Pretoria during World War 2.
In 1941, the year he married fellow student Huberte Goote, he founded the tobacco company Voorbrand and in 1943 the investment company Technical and Industrial Investments.
One of Rupert's biggest conservation initiatives was the Peace Parks Foundation, which he set up to drive his vision of conservation areas transcending national boundaries.
He launched the foundation after persuading the then Mozambican president, Samora Machel, and later Mandela, of his vision for vast cross-border parks in southern Africa that would promote biodiversity conservation and have huge socio-economic benefits for the people of the region.
There are already four such areas involving South Africa and its neighbours - Mozambique, Lesotho, Botswana and Namibia - and others are well advanced.
Foundation chief executive Willem van Riet described Rupert's death as "an enormous loss".
"He was the man who produced the dream and he asked us to turn it into a reality, and that partnership between the dreamers and those making it a reality was extremely strong."
Van Riet said they had been working closely with Johann Rupert, who now heads the business empire, for six months.
"I'm convinced that the staff at the Peace Parks Foundation will work to make this a monument to him."
Malcolm Powell, chief executive of the Wildlife and Environment Society of SA (Wessa), said Rupert had supported the society over many years.
"We obviously had great admiration for him - he really was a great conservationist."