Winnie Madikizela-Mandela was a "solid rock and defender of the vulnerable and defenceless", Parliament's presiding officers have said.

National Assembly Speaker Baleka Mbete and National Council of Provinces chairperson Thandi Modise both expressed shock over the death of the struggle icon.

"She defied the repressive laws and associated patriarchy, embodied a brave character of an unflinching woman in the wake of all odds against her throughout her life," they said in a joint statement.

The 81-year-old, also known as the Mother of the Nation, died on Monday after a long illness.

Mbete and Modise said Madikizela-Mandela had "curved her niche role in shaping the struggle for freedom and in efforts to realise the new free and democratic South Africa".

They described her as an inspiration to "millions of down-trodden women across the length and breadth of the country, across the continent and the world".

"Her vibrancy, unending inner and outer beauty, her passionate connection with ordinary citizens, and her witty and critical mind had contributed in keeping the critical solidarity of the women of South Africa in every facet of life.

"She will be greatly missed, and Parliament trusts that together we will cherish and celebrate her life. Today, we have indeed lost a great leader, a champion of freedom and development, a people’s hero, and a mother, and a defender of the down-trodden."