Two men have vandalised a portrait of South African president Jacob Zuma with his genitals exposed, intensifying a heated debate about the artwork that has enraged the ruling African National Congress.
Television footage showed a white middle-aged man in a suit walking up to the portrait at a Johannesburg gallery and painting a red cross on president's face and private parts.
A younger black man then smeared black paint over the picture while the first man was being taken into custody by security guards.
Iman Rapetti, a reporter for the local eNews channel who witnessed the incident, said: "I was stupefied and screamed for gallery security to apprehend the man."
Mr Zuma and his African National Congress (ANC) have launched a legal bid to have the painting removed from the Goodman Gallery.
The president, who has a reputation for promiscuity, took the depiction of him very personally and compared himself somewhat ironically to a rape victim.
Mr Zuma himself was put on trial for rape, and acquitted, in 2006.
"The portrayal has ridiculed and caused me humiliation and indignity," Mr Zuma, who has been married six times and fathered 21 children, contended in an affidavit filed with the South Gauteng High Court in Johannesburg.
The picture of Mr Zuma, called The Spear, is a facsimile of a famous poster of communist revolutionary Vladimir Lenin.
It is part of a wider exhibition addressing the perception of endemic corruption in Nelson Mandela's former liberation movement.
In the red, black and yellow painting, the president is shown striking Lenin's heroic stance, but with his penis hanging out of his trousers.
The artist, Brett Murray, is well-known in South Africa for his work criticising the white-minority apartheid government that ended in 1994.
Minutes before the vandal attack, ANC secretary general Gwede Mantashe said people had a right to criticise the government, but there were limits.
When you had an artist depicting the president's genitals, he added, "you are not raising a discussion, you are insulting people".
The two men were taken into police custody. Police did not comment on what charges they might face.