President Jacob Zuma's 'love-child' drama has taken a surprising twist.

The Times newspaper claims Zuma and the daughter of soccer boss Irvin Khoza, Sonono, are already married.

It emerged at the weekend that the couple may have a four-month-old daughter, Thandekile Matina Zuma.

The newspaper has published a copy of what appears to be the child's birth certificate which shows that her parents are married under customary law.

A Department of Home Affairs official says that the document, which was faxed anonymously to the newspaper, appears to be authentic.

A box on the document marked "I hereby declare that I am the natural father of the above child" is signed by "JG Zuma".

In the section "Nature of Marriage", the option "customary" is checked.

Meanwhile, Deputy President Kgalema Motlanthe told Eyewitness News the African National Congress does not know if Zuma has in fact fathered a love child.

The ANC said Zuma's personal life is private while its youth league said no one should question their elders about their sex lives.

Motlanthe admits he was not even sure if any of the recent reports about the affair were actually true.

"We don't even know if this is fact or fiction," he said.