President Jacob Zuma paid tribute to African National Congress (ANC) stalwart Albertina Sisulu on Friday after her death at her home in Linden, Johannesburg, at the age of 92.

"A matriarch and a nurse by profession, Mama Sisulu was one of the foremost mothers of the nation and the last of the colossuses of the struggle for the liberation of South Africa," Zuma said in a statement.

He said Sisulu had, over the decades, been "a pillar of strength not only for the Sisulu family, but also the entire liberation movement as she reared, counselled, nursed and educated most of the leaders and founders of the democratic South Africa".

"While we mourn her loss, we must thank her most profoundly for the selfless service to all South Africans and humanity at large, for her generosity of spirit and for teaching the nation humility, respect for human dignity and compassion for the weak, the poor and the downtrodden."

Zuma said that as a former president of the United Democratic Front and together with her husband Walter Sisulu, a former ANC president who died at the age of 90 in 2003, Albertina Sisulu dedicated her adult life to the struggle for liberation in South Africa.

The Sisulus spent most of their lives as ambassadors and leaders of the ANC, but in the process endured decades of banishment, detention, humiliation and exile.

Zuma said South Africa remained eternally grateful and indebted to Albertina Sisulu, a stalwart of the liberation.

"On behalf of government and the people of South Africa, we would like to convey our deepest condolences to the Sisulu family and thank them profusely for dedicated their daughter, mother and grandmother to the service of humanity," Zuma said.

After her death on Thursday one of her sons, Mlungisi, told the SABC: "Mama was sitting in a chair watching the news as they prepared supper. And you know, all of a sudden she slumped to one side... Paramedics were called. In the house she was with two of her grandchildren... and the ladies who keep the house."

Another of her children, her daughter Beryl, who is South Africa's ambassador to Norway, said: "I think I'm still in shock because I was talking to my sister who was in the same room with her and she said she was fine, and the next 20 minutes you hear that she passed away."

Family started arriving at Sisulu's house on Friday morning.