As one world leader after another paid homage to Nelson Mandela at a memorial service, the man standing at arm's length from them appeared to interpret their words in sign language. But advocates for the deaf say he was a faker.

The incident, which outraged deaf people and sign-language interpreters watching the service broadcast around the globe, raised questions of how the unidentified man managed to crash a supposedly secure event attended by scores of heads of state.

It also was another example of the problems plaguing Tuesday's memorial, including public transportation breakdowns that hindered mourners going to the soccer stadium and a faulty audio system that made the speeches inaudible for many. Police also failed to search the first wave of crowds who rushed into the stadium after the gates were opened just after dawn. 

'Only he can understand those gestures.' - Nicole Du Toit, official sign language interpreter

The man, who stood about one metre from many world leaders, including U.S. President Barack Obama, "was moving his hands around, but there was no meaning in what he used his hands for," Bruno Druchen, national director of the Deaf Federation of South Africa, told The Associated Press on Wednesday.

When South African Deputy President Cyril Rampaphosa told the crowd that former South African President F.W. de Klerk was among the guests, the man at his side used a strange pushing motion unknown in sign language that did not identify de Klerk or say anything about his presence, said Ingrid Parkin, principal of the St. Vincent School for the Deaf in Johannesburg.

South Africa Mandela Interpreter

The closest the man's gestures came to anything in sign language at that point might possibly be the words for "running horse," "friend" or "beyond," she said, but only by someone who signs terribly. 

The man also used virtually no facial expressions to convey the often-emotional speeches, an absolute must for sign-language interpreters, Parkin said..

Nicole Du Toit, an official sign language interpreter who also watched the broadcast, said in a telephone interview that the man on stage purporting to sign was an embarrassment.

"It was horrible, an absolute circus, really, really bad," she said. "Only he can understand those gestures."

U.S. Secret Service spokesman Ed Donovan said in response to an emailed question by the AP that "agreed-upon security measures between the U.S. Secret Service and South African government security officials were in place" during the service.

"Program items such as stage participants or sign-language interpreters were the responsibility of the host organizing committee," Donovan added.

The man also did sign interpretation at an event last year that was attended by South African President Jacob Zuma, Druchen said. At that appearance, a deaf person in the audience videotaped the event and gave it to the federation for the deaf, which analyzed the video, prepared a report about it and a submitted a formal complaint to the ANC, Druchen said.

In their complaint, the federation suggested that the man should take the five years of training needed to become a qualified sign language interpreter in South Africa. But the ANC never responded, Druchen said.

Druchen said a fresh complaint will be filed to the ANC about the interpreter he called a "fake" with a demand for an urgent meeting.

"We want to make a statement that this is a warning to other sign language interpreters who are fake and go about interpreting," Druchen said. "I am hoping the South African government will take notice of this."

Bogus sign language interpreters are a problem in South Africa, because people who know a few signs try to pass themselves off as interpreters, said Parkin, the principal of the school for the deaf. And those hiring them usually don't sign, so they have no idea that the people they are hiring cannot do the job, she said.

"They advertise themselves as interpreters because they know 10 signs and they can make some quick money," said Parkin. "It is plain and simple abuse of the deaf community, they are taking advantage of the deaf community to make money."