South African anti-apartheid campaigner Winnie Madikizela-Mandela has died aged 81, her personal assistant says.
Winnie Madikizela-Mandela was the former wife of South Africa's first black president, Nelson Mandela.
The couple – famously pictured hand-in-hand as Mr Mandela walked free from prison after 27 years – were a symbol of the anti-apartheid struggle for nearly three decades.
However, in later years her reputation became tainted legally and politically.
Family spokesman Victor Dlamini said Mrs Mandela "succumbed peacefully in the early hours of Monday afternoon surrounded by her family and loved ones" following a long illness, which had seen her go in and out of hospital since the start of the year.
Retired archbishop and Nobel laureate Desmond Tutu praised her as a "defining symbol of the struggle against apartheid".
"Her courageous defiance was deeply inspirational to me, and to generations of activists," he added.
President Cyril Ramaphosa – who Mrs Madikizela-Mandela praised earlier this year – is expected to visit the family home this evening, African National Congress (ANC) chairperson Gwede Mantashe said.
He added: "With the departure of Mama Winnie, [we have lost] one of the very few who are left of our stalwarts and icons. She was one of those who would tell us exactly what is wrong and right, and we are going to be missing that guidance."
Energy Minister Jeff Radebe, reading out a statement on behalf of the family, paid tribute to "a colossus who strode the Southern African political landscape".
"As the ANC we dip our revolutionary banner in salute of this great icon of our liberation struggle," he said.
"The Mandela family are deeply grateful for the gift of her life and even as our hearts break at her passing we urge all those who loved her to celebrate this most remarkable South African woman."