Concerns over the male interpreter had been raised by deaf people watching the service at Johannesburg's FNB Stadium on Tuesday. There are claims the sign language interpreter did not follow what the speakers were saying, with some commentators even alleging he was making the interpretation up.

Bruno Druchen, national director of the Deaf Federation of South Africa, said the unidentified man - who was on stage alongside world leaders including US President Barack Obama - "was moving his hands around but there was no meaning in what he used his hands for".

South African parliament member Wilma Newhoudt-Druchen, a member of the ruling party, also said the man communicated nothing with his hand and arm movements.

Both Mr Druchen and Ms Newhoudt are deaf. A government spokesman says it will "get to the bottom" of the claims.