In pictures: Mandela turns 91

Members of the ANC executive committee and other guests

Leading figures from the African National Congress, family and friends gathered to help Nelson Mandela celebrate his 91st birthday at his Johannesburg home on Saturday

A steady stream of well-wishers arrived at Mr Mandela's house in Houghton, and Happy Birthday was sung - in English and his native Xhosa tongue

Mandela's daughter Zenani (l) greets her mother Winnie, as Mandela's grandson Mandla looks on

Family members were well represented, and Mr Mandela's former wife Winnie Madikizela also paid a birthday visit

Nelson Mandeal, with wife Graca Machel, blows out candles on birthday cake

Despite increasing frailty, Mr Mandela got down to the serious business of blowing out candles on his ANC-themed cake - but may have been relieved not to have to deal with a full set of 91

An "inspiration to the world", was the tribute from President Jacob Zuma, who was among those who dropped in for the celebrations

Children at a soup kitchen on the outskirts of Cape Town, under an initiative to celebrate Nelson Mandela's birthday

This year South Africa is marking 18 July as Mandela Day - when people are encouraged to do voluntary work in their own communities, for example at this soup kitchen

Voluntary helper at a Khayelitsha animal clinic

The Nelson Mandela Foundation hopes Mandela Day will become an annual event and that people around the world will take up the challenge

Singer Will.I.Am performs at the Mandela day in New York

Later, in New York, artists and musicians, including singer Will.I.Am, Wyclef Jean, Lil' Kim and Gloria Gaynor, performed at Mandela Day: A 46664 Celebration Concert.

Carla Bruni-Sarkozy performs in New York

Carla Bruni, an international ambassador for HIV/Aids charities, sang in public for the first time since her marriage to French President Nicolas Sarkozy, who was watching the show.