Winnie Madikizela-Mandela, the former wife of Nelson Mandela, South Africa's first black president and human rights icon, has died, her family said Monday. She was 81.

"She succumbed peacefully in the early hours of Monday afternoon surrounded by her family and loved ones," the family said in a statement.

Mandela had been ill for several years and was hospitalized recently with kidney problems, the South African website Eyewitness News said

"She kept the memory of her imprisoned husband Nelson Mandela alive during his years on Robben Island and helped give the struggle for justice in South Africa one its most recognizable faces," the family said.

She dedicated most of her adult life to the cause of the people and for this was known far and wide as the Mother of The Nation," it said.

A longtime stalwart of the ruling African National Congress political party, she was a member of South Africa's parliament at the time of her death.

Nomzamo Winifred Zanyiwe Madikizela was born in a remote part of South Africa called Pondoland on September 26, 1936.

She joined the struggle to end apartheid after working as a hospital social worker in the 1950s. Around the same time she met her future husband, a lawyer and human rights activist. After he was arrested for his political activities, she raised two young daughters alone.

She was married to Nelson Mandela from 1958 until their divorce in 1996. For 27 years of their marriage, he was imprisoned by the minority-white apartheid regime.

She campaigned for his release and to rally support in South Africa and around the world for the anti-apartheid movement. She was also imprisoned and tortured.

The couple separated after her husband's release in 1990 and he became president of South Africa in 1994. When Mandela sued her for divorce, she protested, but a judge granted the divorce. He died in 2013.

She kept his surname and they maintained ties, but critics accused her of attempting to use his name for political mileage. Her reputation later became tainted by a fraud conviction and murder accusations, which she denied.