US First Lady Michelle Obama has received a warm welcome in South Africa at the start of a two-nation tour. She is travelling with her mother, two daughters and nephews on a trip to champion the importance of youth leadership across Africa. Mrs Obama is expected to visit Soweto and Robben Island where ex-President Nelson Mandela spent 18 years of his 27 years in jail. She is also due to meet current leader Jacob Zuma before going to Botswana. Symbolism As Mrs Obama was greeted at a military airport in the capital, Pretoria, her daughters Malia and Sasha were given large blankets with colours of the South African flag to ward off the chill. The trip to South Africa is her second official solo visit abroad since her husband Barack Obama became president in 2009. The BBC's Karen Allen in Johannesburg says it is expected to be packed with symbolism. The first lady will visit the apartheid museum in Johannesburg and the township of Soweto, which lay at the heart of the fight against white minority rule. She will be meeting Graca Machel, Mr Mandela's wife, though it is not yet clear whether she will have the opportunity to meet the elderly statesman himself. Mr Mandela is 92, frail, and rarely receives visitors. The first lady is seen as role model in her own right and will meet South Africa's young women leaders on Wednesday as she makes her keynote address, our correspondent says. "This trip by the first lady is very directly connected to the president's agenda in Africa and the Obama administration's foreign policy in Africa," Mr Obama's deputy national security adviser Ben Rhodes said last week, according to Reuters news agency. "It's no coincidence that she would be visiting countries that have embraced democracy," he said. Source: BBC