Cartoonist Zapiro said his critics misinterpreted his presidential pardon cartoon. The Mail & Guardian published the picture showing convicted fraudster Schabir Shaik and Apartheid hitman Eugene de Kock holding down a female caricature of justice.

President Jacob Zuma is sketched standing over them, undoing his belt buckle while saying "begging your pardon".

Jonathan Shapiro said the sketch was not done on impulse.

"I put a lot of thought into it as always with a controversial drawing like this. I spoke at length with my editor to look at whether the cartoon works and whether it is justifiable in terms of what is being debated in the public domain," he said.

The National Union of Metal Workers has called on Zaprio to apologise for what they have call a "reckless cartoon".

Spokesperson Castro Ngobese said the drawing goes beyond freedom of expression. "We can not hide under freedom of expression and so forth. That cartoon borders on defamation of character," he commented.