Last week Mr Zuma defended himself against accusations that polygamy was "a step backward" or unfair to women in a discussion at the World Economic Forum in Davos.

"People interpret cultures in different ways," he said. "Some think that their culture is superior to others, that's a problem we have in the world."

In South Africa, he went on, "we follow a policy that says you must respect the cultures of others. That's my culture. It does not take anything from me, from my political beliefs and everything, including the belief on the equality of women".

Mr Zuma's personal life is not an issue for most South Africans. But Helen Zille, the leader of the opposition Democratic Alliance, said that it was counterproductive given the country's fight against HIV-Aids.

"There are some people who may argue that Jacob Zuma's sex life is a matter of private morality or 'culture', but this is not so," she claimed.

Pointing out that after his rape trial, when he was acquitted, he had apologised for having unprotected sex with the HIV-positive daughter of a family friend, she added: "He has once again succeeded in sending the wrong message to the South African people."

Mr Zuma's spokesman, Vincent Magwenya, could not be reached for comment on Sunday.