JOHANNESBURG, South Africa – Zindzi Mandela, the youngest daughter of South Africa’s first black president Nelson Mandela has died aged 59.

She was ambassador to Denmark at the time of her death.

“The 59-year-old daughter of former president Nelson Mandela and struggle stalwart Winnie Madikizela-Mandela, passed away at a Johannesburg hospital in the early hours of this morning,” said public broadcaster SABC.

The cause of her death was not immediately revealed.

The Mandelas’ daughter came to international prominence in 1985, when the white minority government offered to release Nelson Mandela from prison if he denounced violence perpetrated by his movement, the Africa National Congress, against apartheid, the brutal system of racial discrimination enforced in South Africa at that time.

Zindzi Mandela read his letter rejecting the offer at a packed public meeting that was broadcast around the world.

She is survived by her husband and four children.