Guests stood and cheered, a Xhosa choir sang and a smiling Nelson Mandela welcomed hundreds of well-wishers in a festive tent outside his home on Saturday as South Africa formally celebrated the anti-apartheid icon's 90th birthday.

Mandela -- walking in with his successor as South Africa's president, Thabo Mbeki, and African National Congress (ANC) leader Jacob Zuma -- stopped to personally greet a few of the 500 honoured guests as he made his way to the head table.

Some guests had come to the party in exquisitely beaded traditional wear, others wore T-shirts emblazoned with his name. Mandela wore an intricately patterned shirt in shades of brown.

The Nobel Peace Prize winner had celebrated privately with his family in his home village in the Eastern Cape on Friday, the day he turned 90. Saturday was a grand occasion at his homestead in Qunu, 1 000km south of Johannesburg, where as a boy he herded cattle in the hills.

The party tent was decorated with the blue and orange colours of Mandela's Xhosa tribe and with his clan's crest -- a bee flanked by tree branches, symbolising industry, community and strength.

Advocate George Bizos was among the fellow veterans of the struggle to transform South Africa from a white supremacist pariah nation into a multiracial democracy who came to the party on Saturday. He identified Mandela's optimism as his most "sterling quality".

"He always believed that there would be freedom around the corner," said Bizos, a lawyer who defended Mandela and other anti-apartheid leaders during the era of white rule.

Tributes from Mbeki and others and performances by choirs and dancers were planned under the tent. As the party started, herd boys beat drums outside, while an orchestra played inside.

"Clearly, today [Saturday] is a very special day for all of us in South Africa and around the world," said Mac Maharaj, who served time with Mandela on Robben Island, and then served in Mandela's Cabinet.

Symbol and embodiment of hope
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, and was then 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 honoured guest for a huge charity concert in London's Hyde Park.

"For a man of 90, he's in very good shape," one of his doctors, Peter Friedland, said at the party on Saturday.

He looked and sounded vigorous on Friday when he gave a brief interview to a small group of reporters, his first such exchange in several years. He was expected to address the party guests later on Saturday.

During Friday's interview, he expressed deep concern at the poverty that still grips South Africa. The economy has grown steadily in recent years, but the benefits have yet to trickle to the poorest.

Mandela's message was simple -- the wealthy must do more.

"There are many people in South Africa who are rich and who can share those riches with those not so fortunate, who have not been able to conquer poverty," Mandela said on Friday.

Friday was also the 10th anniversary of his marriage to his third wife, Graca Machel.

Meanwhile, Zuma said at the birthday celebration that Mandela's legacy reminds leaders to lead by the will of the people, defend democracy and never discriminate.

He said Mandela's legacy reminded us that we must never discriminate against other people, no matter how unimportant we may think they are.

Zuma said: "We are here to celebrate a life and legacy of a father, grandfather, comrade, warrior, soldier, nation-builder and statesman.

"We are celebrating the life of man who became a symbol and embodiment of hope for African people in particular, and the ANC in general -- a symbol of sacrifice, unity and of liberation.

"You are the glue that holds us together as a nation. You provide eternal hope in our people and the world, that South Africa can only be a better place each day," said Zuma. -- Sapa-AP