JOHANNESBURG — A healthy-looking Nelson Mandela met with Michelle Obama and her daughters on Tuesday, an unexpected encounter between the First Lady and the former South African president and anti-apartheid icon who has largely retired from public life, the Associated Press reported.

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, 12, and Sasha, 10, and her mother, Marian Robinson, were viewing some of Mandela’s personal papers at his foundation 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 former political prisoner who became his country’s first black president Mrs. Obama’s entourage 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.

White House officials had no immediate comment on the meeting. No aides, except for photographers for the foundation and the White House, witnessed the meeting.

Mandela, who stepped down in 1999 after serving one term as president, is rarely seen in public anymore. At 92, 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 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 Mandela’s book, Conversations with Myself.

Mandela spent 27 years in prison for his role in the movement 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 wives. She and her family were ending the day with a tour of the Apartheid Museum.

Meanwhile, speaking at a Soweto church thrust onto the front lines of the fight against apartheid, the First Lady urged young South Africans to conquer hunger and AIDS and to end violence against women.

While addressing a crowded Regina Mundi Church, she singled out 76 young women from across Africa here for a U.S.-sponsored leadership forum.

The Catholic church, still wearing battle scars from the 35-year-old Soweto uprising and ensuing protests, is named “Regina Mundi,” which is Latin for “Queen of the World.”

She was introduced by Machel, who told her, “We welcome you as a daughter of Africa — and we can call you the ‘queen of our world.’”

Obama told those gathered to work to eliminate poverty, inequality and injustice, ending the 34-minute address by reprising her husband’s 2008 campaign slogan, four times exhorting them:

“Yes we can.
“Yes we can.
“Yes we can.
“Yes we can.
“Yes we can.”

A White House official put the crowd count in Regina Mundi at 2,000.

The Young African Women Leaders Forum, the first of its kind, is being sponsored by the White House, the State Department and other U.S. entities.

The participants, from 24 countries, work in education, health, business and the media.

Obama on Wednesday paid homage to a 13-year-old boy killed by police in 1976 after he was swept up in the spasm of a street protest triggered by a law requiring students to abandon local languages and study in Afrikaans, the language of the descendants of Dutch settlers. Even some exams were written in Afrikaans.

Thirty-five years later, Hector Pieterson lives on as an enduring symbol of the bloody clashes that came before the slow death of apartheid. The teen’s slaying spawned the “Soweto uprising,” local demonstrations that caught fire across the country.

Hector is immortalized not least because of a photo showing an 18-year-old student carrying his lifeless body as Hector’s distraught sister runs alongside.

That sister, Antoinette Sithole, accompanied Obama as she laid a wreath at her brother’s memorial in  Soweto a few hundred yards from where he was gunned down.

The First Lady and five family members with her on the trip to Africa later toured the adjacent museum that lets the world know about Hector’s short life and bloody death.

Photo by AP Photo/ Debbie Yazbek, Nelson Mandela Foundation

First Lady Michelle Obama, left, meets former South African President Nelson Mandela at his home in Houghton, South Africa. Obama and her family are on a one-week trip to parts of Africa.