The meeting lasted about 20 minutes. Mrs Obama also met Nompumelelo Ntuli Zuma, one of President Jacob Zuma's wives

US First Lady Michelle Obama paid a visit to Nelson Mandela yesterday, kicking off her own symbolic trip to Africa by meeting one of the continent's most revered leaders.

Obama, accompanied by her mother and two daughters, visited the 92-year-old anti-apartheid icon at his home in Johannesburg's Houghton suburb.

Pictures released by the Nelson Mandela Foundation showed a smiling Mandela sitting upright on a couch next to the US First Lady and her children.

He was dressed in a brightly coloured shirt - known as a "Madiba shirt" after his clan name used by most South Africans.

The meeting, which included Obama's niece and nephew, who are also travelling with her, lasted about 20 minutes.

Mandela has not been seen in public since he was hospitalised at the start of the year, suffering from a respiratory disease.

He paid a visit to his home village last month, the first since he spent several days in hospital in January.

Since then he has received medical care at his Houghton home.

Mandela retired from public life in June 2004 before his 86th birthday.

White House officials had hoped Obama would be able to see Mandela during her trip, but the meeting was not confirmed until midday yesterday.

Mandela was South Africa's first black president. President Barack Obama is the first US black president, and his wife is the first black presidential spouse.

Mandela met President Obama in Washington in 2005 when he was a senator. A picture of the two men is kept in Mandela's office, according to a White House aide.

Earlier Obama visited the foundation offices, viewing a display of archival items including Mandela's prison desk calendars and notebooks.

Mandela's wife, Graca Machel, showed the Obama family around the exhibits.

The US First Lady arrived in South Africa late on Monday and earlier met Nompumelelo Zuma, one of President Jacob Zuma's wives, in Pretoria.