Nelson Mandela's granddaughter Ndileka Mandela turns her back on South Africa's ruling African National Congress (ANC)

South African President Jacob Zuma. Photo / AP

Nelson Mandela's eldest granddaughter has said she will no longer vote for South Africa's ruling African National Congress (ANC), claiming the party no longer holds the values for which her grandfather fought.

Ndileka Mandela, 52, a nurse who runs a Mandela family foundation to help the rural poor, said she had been left despondent by the ANC-led Government, which she said was squandering public money and neglecting the impoverished.

"This is not a decision that has been made out of anger," said Mandela, who is the first in the family to reject the ANC. "I've been thinking about it for a while. It's been a build up."

She said worthwhile projects in rural areas were always held up by a lack of funding, yet the Government, led by President Jacob Zuma, was wasting billions of rand.

The ANC's callousness after a government blunder caused the deaths of 96 state psychiatric patients in Gauteng province last year was the tipping point in her decision, she added.

Many of the bodies of the patients were founds to have head injuries and unexplained bruises. At the opening of Parliament in February, the ANC-elected speaker refused a request from MPs to hold a moment of silence for the patients.The patients were part of a group of 1300 who were transferred from a private hospital to 27 charitable organisations as a way of saving money.

"For me it's a problem of accountability," she told the News24 site. "It's one scandal after the next and there's no accountability. And our people suffer for it."

Mandela, whose father died in a car accident in 1969, said her grandfather would never have supported blind loyalty.

She does not yet know who she will vote for, but said she is looking for a party that will lift rural areas. "I will not be voting for something that does not resonate with me any more, and does not resonate for what granddad and his comrades fought for," she said.

The ANC has been beset with corruption scandals since Zuma, 74, was elected to office in 2009. Last year the country's highest court found that he had violated his oath of office by refusing to abide by a state watchdog's report on paying back public money spent on upgrading his rural home.

In September last year, Zuma paid back 7.8-million rand for the upgrades, which included a swimming pool and state of the art chicken coup.

He also faces the reinstatement of 783 corruption charges linked to multi-billion-pound arms deals nearly 20 years ago.

The party, which has won every election since 1994 with more than 60 per cent of the vote, suffered its worst ever result last August by losing the key municipalities of Johannesburg, Pretoria and Port Elizabeth to the opposition Democratic Alliance party.

Mandela, who died in 2013, was elected South Africa's first black president in 1994 after spending decades in prison for fighting against white rule.