500 guests party with Mandela for his 90th

Eager to thank his guests, Mandela rose to his feet and spoke for a few minutes with his characteristic self-deprecating humor.

"As you know I am not a speaker at all, and I am not going to make any exception on this occasion, except to say thank you for all you have done for me," he said.

Mandela was imprisoned for nearly three decades for his fight against apartheid. He was released in 1990 to lead negotiations that ended decades of racist white rule, then was elected president in South Africa's first democratic elections in 1994.

He completed his term in 1999 and did not run again, but has continued to take a leading role in the fight against poverty, illiteracy and AIDS in Africa. Age has slowed him in recent years, but many still remain in awe of his stamina. Just last month, he was the honored guest for a huge charity concert in London's Hyde Park.

"I would say that for a 90-year-old man who has been through what he has been through, he is in exceptional shape," one of his doctors, Peter Friedland, said at the party Saturday.

Mandela looked and sounded vigorous Friday when he gave a brief interview to a small group of reporters from The Associated Press and other media, his first such exchange in several years.

During Friday's interview, he expressed deep concern about the poverty that still grips wide swaths of South Africa and said the wealthy must do more.

While Saturday's occasion was celebratory, there were also a few somber moments.

Nandi Mandela called on her grandfather's fans to emulate him by "making a difference in your own communities."

"This is one of the gifts you can give him," she said as her grandfather nodded.

George Bizos, a lawyer who defended Mandela and other anti-apartheid leaders during the era of white rule, urged young and old to try and understand what his old friend stood for.

"It's the solution to the problems that are facing the country, facing the continent, facing the world," he said.

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