Winnie Madikizela-Mandela, the ex-wife of Nelson Mandela, has been hospitalised and is due to undergo surgery for a broken wrist, her daughter said on Saturday.

"Mrs Winnie Madikizela-Mandela is in hospital with a broken right wrist following a fall on Thursday," said Zindzi Mandela in a statement issued via her former husband's foundation.

She will be operated on on Monday, it said, without specifying the hospital where she had been admitted.

Madikizela-Mandela, 75, was last September briefly hospitalised for a foot operation and in November she went into a Johannesburg hospital for treatment for diabetes.

She was married to ex-president Nelson Mandela from 1957 to 1996, although they had officially separated four years earlier. She had tirelessly campaigned for his release during his 27-year imprisonment under apartheid.

Her image was tarnished by a series of scandals, including her links to the kidnap and murder of a young activist and a 2003 fraud conviction.

But she remains an influential figure as a lawmaker and a member of the ruling African National Congress party's national executive committee.