Evidence suggesting that President Jacob Zuma and Sonono Khoza are married according to customary law has reportedly been sent to a daily newspaper.

The document, apparently a copy of their application for a birth certificate for their daughter Thandekile Matina Zuma has the answer "yes" in reply to the question: "Are the parents of the child married to each other."

The document was reportedly signed by Zuma and Khoza.

Under "Nature of Marriage" the option "customary" was checked, according to The Times.

The document is reportedly dated January 19 - just days after the president's motorcade is said to have arrived at the Khoza family's mansion in Diepkloof Extension, Soweto.

It was also signed by an official at the Home Affairs office in Randburg.