In this photo provided by the Nelson Mandel Foundation on Tuesday, June 21, 2011, US First Lady Michelle Obama centre, accompanied by her daughters, Malia, left and Sasha, meet former South African President Nelson Mandela, at this home, in Houghton, South Africa. First lady Michelle Obama and her family met with Nelson Mandela during a private visit at the former South African president's home. Mrs. Obama, daughters Malia and Sasha, and her mother, Marian Robinson, were viewing some of Mandela's personal papers at his foundation Tuesday when according to White House officials, he sent word that he wanted to meet them. It was Mrs. Obama's first meeting with the prisoner-turned-president. (AP Photo/ Debbie Yazbek, Nelson Mandela Foundation)

JOHANNESBURG (AP) — A healthy-looking Nelson Mandela met on Tuesday with first lady Michelle Obama and her daughters — an unexpected encounter with the former South African president and anti-apartheid icon who has largely retired from public life.

A photo provided by the Nelson Mandela Foundation showed the 92-year-old Mandela sitting on a couch next to Mrs. Obama, pen in hand to sign an advance copy of his new book, "Nelson Mandela By Himself: The Authorized Quotations Book." Mandela was wearing one of his trademark shirts, richly patterned and buttoned at the neck.

Mrs. Obama, daughters Malia and Sasha, and her mother, Marian Robinson, were viewing some of Mandela's personal papers at his foundation Tuesday when he sent word that he wanted to meet them at his home in a leafy Johannesburg neighborhood. It was the first meeting between America's first black first lady and the political prisoner who later became his country's first black president.

The American president's family spent about 20 minutes with Mandela and his wife, Graca Machel, who is a former first lady of Mozambique.

Mrs. Obama's niece and nephew, Leslie Robinson, 15, and Avery Robinson, 19, who are traveling with her, were also invited to meet Mandela.

Mandela, who stepped down in 1999 after serving one term as president, is rarely seen in public anymore. He is in fragile health and was briefly hospitalized in January with an acute respiratory infection. But he apparently felt well enough Tuesday to invite the Obama family to visit.

Mrs. Obama is traveling without President Barack Obama, who met Mandela on a previous visit to Africa when he was a U.S. senator. Obama and Mandela have spoken by telephone several times since Obama took office, most recently last June, the White House said. Obama also wrote a foreword for another Mandela book, "Conversations with Myself."

Mandela spent 27 years in prison for leading the struggle against apartheid, South Africa's now-abolished system of racial separation.

Mrs. Obama began a weeklong goodwill visit to South Africa and Botswana on Monday.

Earlier Tuesday, the first lady met with Nompumelelo Ntuli-Zuma, a wife of South African President Jacob Zuma, who has three of them. Mrs. Ntuli-Zuma is the South African president's third wife.

Mrs. Obama and her family were ending the day with a tour of the Apartheid Museum.

Copyright 2011 The Associated Press.