Pretoria - United States Senator Edward Kennedy was a comrade of South Africa in its liberation struggle, President Jacob Zuma said on Wednesday.
"For South Africa, he became a comrade and a friend in the fight for liberation," said the President in a statement on Wednesday evening.
He said it was due to his strong belief that all people are born equal and his nature, which did not allow him to rest in the face of injustice.
Mr Zuma expressed his condolences to the Kennedy family. "We grieve the loss of this great man but the legacy of his contribution to this world will continue to serve as a sort of hope to us," he said.
Mr Kennedy died at 77, late Wednesday at home in Hyannis Port, Massachusetts, after fighting brain cancer for more than a year.
Nicknamed "Teddy", Mr Kennedy was the brother of former US President John Kennedy who was assassinated in 1963. He was the last of the Kennedy brothers in the legendary family and known as "The Lion of the Senate."
"We remain grateful for his role," said President Zuma.
Mr Kennedy's contribution to American and global politics has been praised since his death.
Achmat Dangor, Chief Executive Officer of the Nelson Mandela Foundation in South Africa, said he had been "a champion of democracy and civil rights."
"We mourn, with his family, and the United States of America, the loss of a champion of democracy and civil rights. He made his voice heard in the struggle against apartheid at a time when the freedom struggle was not widely supported in the West," the foundation said.
US President Barack Obama, who was on vacation at an East Coast resort, said his family was "heartbroken" at the news.
An important chapter in our history has come to an end. Our country has lost a great leader, who picked up the torch of his fallen brothers and became the greatest United States Senator of our time.
"For five decades, virtually every major piece of legislation to advance the civil rights, health and economic well-being of the American people bore his name and resulted from his efforts," said President Obama.
United Nations Secretary General Ban Ki-moon praised Kennedy for keeping and upholding the ideals and goals of the United Nations.
He said his work would be long remembered in the minds and in the hearts of many people, particularly vulnerable people, and those people whose human rights have been abused.
"He had been the voice of the voiceless and the defender of many defenseless people."
Mr Kennedy's funeral will be held on 29 August at a historic Boston church and he will be buried at Arlington National Cemetery, where his two slain brothers are laid to rest.