It is the meaning of what my life has been since youth,to try to fight for the dignity and the freedom of my own people

Graca Machel

Those who have seen her in action say she does not flinch from challenging diplomats for sitting back in the comfort of their embassies while children in conflict are exploited and killed.

Her first husband was the founding president of Mozambique, the late Samora Machel, who died in a plane crash over South Africa in 1986 and was a staunch supporter of the anti-apartheid struggle.

She believes that Mr Machel was assassinated as a result of a conspiracy involving agents from Mozambique, South Africa and Malawi.

< Giving evidence to the South African Truth and Reconciliation Commission, which also looked into her late husband's death, Graca Machel sometimes broke down in tears.

Human rights

Graca Machel posing outside the home of Mr Mandela

In December 1997 she gave her support to a commemorative programme marking the 50th anniversary of the universal declaration of human rights.

She defined her support as a part of a lifetime commitment: "It is the meaning of what my life has been since my youth, to try to fight for the dignity and the freedom of my own people."

Graca Machel produced a report in 1996 on the impact of armed conflict on children.

Some say that report was a cry from the heart, for she witnessed at first hand the misery such wars caused on the children of Mozambique where she was a member of the liberation struggle and became a minister of education.

Second marriage

Nelson Mandela: "She changed my life"

She steadfastly refused to comment publicly on her relationship with Mr Mandela at a time when the press was full of stories about their romance.

It is understood Graca Machel, 55, had resisted becoming Mr Mandela's third wife because she felt it would have been wrong to marry him whilst he was still head of state in South Africa.

She finally tied the knot in July 1998 and although she had lived with the former South African president at his house in Johannesburg before that, she nevertheless took him to Mozambique for a traditional blessing.

Back there she is well respected as a positive influence and a role model for young women.

Those of her compatriots - and they are few - who do not approve her union with Mr Mandela call her ambitious.

Graca Marchel has proved a tower of strength and a confidante of the ailing Mr Mandela who even before their wedding travelled with her across the world stage. He once said of her: "She is my life".

I once met her when she came to be interviewed at the BBC in Bush House following a children's conference she had just attended. She looked radiant with a big smile. I remember her indulging us journalists as we lined up to talk to her.

A friend who had dinner with Graca Machel described her as unpretentious with a young girlish giggle.

As Mr Mandela takes up the role of ambassador for Unicef, the United Nations Children's Fund, he will surely have an ally in Graca Machel, a partner with a record as a political heavyweight in her own right.