The South African government formally apologised Friday for any offense caused by the sign language interpreter it hired for Nelson Mandela's memorial, later exposed as a fake.

"We sincerely apologise to the deaf community and to all South Africans for any offence that may have been suffered," Arts and Culture Minister Paul Mashatile said in a statement.

The country's junior minister for disabilities, Hendrietta Bogopane-Zulu, admitted on Thursday the government had made a "mistake", but defended the interpreter.

Enraged sign language experts said that Thamsanqa Jantjie's signing in front of US President Barack Obama and other world leaders gathered at Soweto's Soccer City stadium had amounted to little more than "flapping his arms around".

Jantjie later blamed his behaviour on a schizophrenic attack.

Contacted by AFP by telephone on Friday, he refused to discuss the incident, saying he was too busy drafting an explanation to the government.

"Yesterday I explained to all the media...( and) today I am busy with the government that want my side of the story," he said.

Minister Mashatile said parliament would pass a new law early next year to regulate the profession "so that this kind of incident doesn't happen ever again."

Bogopane-Zulu said Thursday the interpreter was not fake, but may have had problems with English or was overworked and tired.

South Africa's deaf organisations, however, said this was not a one-off incident, claiming they had complained to the government about Jantjie before.