Nelson Mandela, the icon of South Africa's struggle against apartheid, marked his 89th birthday on Wednesday by launching his fellow elder statesmen on a new venture to reduce conflict and despair.

The former South African president was the host and star turn at a ceremony in Johannesburg to announce the formation of a brains trust of world leaders, bringing together the likes of former United States president Jimmy Carter and former United Nations chief Kofi Annan, on a mission to tackle some of the world's most pressing problems.

Supported by a walking stick and his wife Graça Machel on their ninth wedding anniversary, Mandela told his guests they could offer both wisdom and independence of thought after a lifetime of public service.

"Together we will work to support courage where there is fear, foster agreement where there is conflict and inspire hope where there is despair," said Mandela as he unveiled the launch of the Elders.

"They don't have careers to build, elections to win and constituencies to please," he said.

"I am confident that the Elders can become a real role model. I wish them well and hope that they succeed in bringing light to some of the darkness that affects our world."

While his opening address was followed by short speeches from fellow luminaries such as Carter and British tycoon Richard Branson, it was the beaming face of Mandela in one of his trademark shirts that stole the show

His successor as president and leader of the governing African National Congress (ANC), Thabo Mbeki, has long struggled to emerge from the shadow of Mandela, but he was among those who paid tribute to the man who is more widely known in South Africa by his clan name Madiba.

"Former president Mandela inspires South Africa, the continent and the rest of humanity through his life, his leadership and his resolute and deep-seated commitment to the struggle against apartheid and for a just and democratic society," Mbeki said.

"The country and the world are privileged to celebrate the life of such an outstanding leader of our people."

'I am a son of Mandela'

After what is becoming an increasingly rare public appearance, Mandela was to spend his evening watching a football match in his honour in Cape Town from the comfort of his living room in Johannesburg.

The celebrations come as a new survey showed the anti-apartheid icon, who spent 27 years behind bars for his role in the fight against the white-only apartheid regime, was more popular than ever -- especially among white people.

Mandela has limited his political activities since announcing his retirement from public life in 2004, although he still releases occasional video messages and holds private audiences with visiting statesmen.

As Mandela was hosting the launch in Johannesburg, a galaxy of stars from the football world, such as Liberian legend George Weah and Cameroon ace Samuel Eto'o, visited the former prison colony on Robben Island where Mandela spent 18 of his 27 years in captivity.

They will later line up at Cape Town's Newlands Stadium for a special "90 Minutes for Mandela" match designed to raise money for his foundation.

Fifa president Sepp Blatter said the match was an opportunity "to honour an extraordinary man who dedicated his lifetime to the promotion of human rights and democracy".

"I am a son of Mandela. He has inspired me. He fought for our continent. He inspired millions over the world," former AC Milan star Weah said.

Pele, who presented Mandela with a commemorative match shirt in Johannesburg on Tuesday, did not make the trip as he suffers from sea sickness.

A survey, meanwhile, published by the researchers Markinor gave Mandela a 92% approval rating among South Africans, including 78% from the white population. That compares with a rating of 32% in 1992, two years after his release from prison. -- AFP