As Nelson Mandela turns 91 on Saturday, his family and his charitable foundation are trying to harness his iconic status around the globe to promote community service on his birthday.

Celebrities and politicians will also be holding concerts and other celebrations from Johannesburg to New York.

But as South Africa's first black president ages, those closest to him are trying to turn his name's magic appeal into an annual "Mandela Day" of service while preventing it from becoming over-commercialised.

"The focus is on community service, picking up the one element of Mr Mandela's legacy that should apply to us all, and that is service to mankind," said Ruth Rensburg of the Nelson Mandela Foundation.

Organisers are asking the public to dedicate 67 minutes to an act of service to others, a minute for every year since Mandela took up the struggle for equality in South Africa.

Mandela's eldest grandson and chief of the Mandela clan, Mandla Zwelivelile Mandela, told Agence France-Presse (AFP) he will spend the day in the Mvezo village, where his grandfather was born, cleaning the graves of his great-great-grandparents.

The younger Mandela said his grandfather, just two weeks ago, came to the village to remind children of the collective struggle against apartheid rule.

"He said: 'There is no leader that exists alone. I existed with ordinary men and women of this country who sacrificed more than I ever did and they just chose me to be the face of this campaign'," said the grandson.

He said Mandela Day should "pay tribute to the collective effort of leadership" that helped bring democracy to South Africa and "be able to plough back to communities where we came from."

Nelson Mandela spent 27 years in prison, emerging in 1990 committed to democracy and negotiating a deal that led to universal suffrage and the country's first black presidency, earning him the Nobel Peace Prize in 1993.

Mandela has officially retired from public life, but his name, image and presence are still sought after, with celebrities wanting to meet him and the African National Congress seeking his continued endorsement.

Great concern
Mandla Mandela, whose father's death of Aids in 2005 prompted the former president to speak out against the stigma of HIV/Aids, is at the centre of a battle for the leader's legacy.

This year he denied reports that he sold the television rights to his grandfather's funeral to the South African Broadcasting Corporation.

Mandla told AFP the rights to his grandfather's name and how it is used was of great concern to the family, warning Mandela Day itself risked "losing its purpose".

"Now people are already seeing this as a profit-making scheme and doing their own initiatives to reap rewards out of this."

Rensburg, of the Nelson Mandela Foundation, says Mandela's intellectual property is in safe hands and was monitored around the world, and stopped where necessary.

A London art gallery has come under fire for displaying prints of artwork that the exhibitors claim were signed by Mandela. His lawyers say the signatures were faked.

"My serious concern is what becomes of the name after the old man has come and gone," said Mandla.

"We currently see that name commercialised, seeing my grandfather printed on coins and things. It is for us as a family to really become active participants as to what we desire for my grandfather's legacy to become." -- AFP