The meeting at his home in Johannesburg came on the second leg of her tour of Africa.

Mrs Clinton hailed Mr Mandela for the personal discipline he showed when he fought South Africa's apartheid system.

She was shown handwritten copies of Mr Mandela's letters from his time as a political prisoner.

Mrs Clinton was also shown his membership card of the Methodist Church, a denomination to which she also belongs.

Referring to these documents, she said: "It of course inspires in me an even greater admiration for his public work but an even greater affection for the man.

"The discipline that he brought to a life filled with so many great achievements, not only for him personally but for South Africa and the world."