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Deaf people watching the Nelson Mandela memorial were bemused and shocked by a "fake" sign language interpreter on stage whose gestures were unintelligible, activists said Wednesday.

The interpreter was watched by millions as he stood beside speakers at the event including President Barack Obama.

Hundreds of people took to social media to express their anger at the interpreter's gestures, and several deaf groups confirmed his signing did not reflect the comments being made to honor the anti-apartheid icon.

Paul Breckell, chief executive of the U.K.-based charity Action on Hearing Loss, said: "We are shocked by the quality of sign language interpretation at Nelson Mandela’s memorial -- if it could be called interpretation at all."

He added that "the limited number of signs, the amount of repetition, lack of facial expressions and huge gaps in translation meant that deaf or hard of hearing people across the world were completely excluded from one of the biggest events in recent history."

Among the first to express their dissatisfaction was Wilma Newhoudt-Druchen, the first deaf woman to be elected to the South African parliament, who tweeted that the signing was "rubbish," adding: "He cannot sign. Please get him off."

She took to the social media site several times during the day.

David Buxton, chief executive of the British Deaf Association, said in an email that "the gentleman is a total fake."

"He has no real clue about sign language and has obviously upset the deaf community of South Africa as we have received hundreds of angry messages via Facebook and Twitter," said Buxton, who was watching the ceremony with his South African-born wife.

Buxton called on the South African authorities to "name and shame that gentleman." He said the same interpreter had provided sign language for South African President Jacob Zuma’s speech at a military event last year.

The South African government said in a statement that it was "looking into this matter but has not been able to conclude this inquiry due to the demanding schedule" organizing the state funeral.

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Braam Jordaan, a profoundly deaf South African citizen and board member of the World Federation of the Deaf Youth Section, explained why it had been so clear to sign language users that the interpretation was not correct.

He told NBC News in an email: "The structure of his hand, facial expressions and the body movements did not follow what the speaker was saying."

South African sign language interpreter Francois Deysel tweeted during the ceremony that the interpreter was "making a mockery of our profession."

Bruno Druchen, the national director of the Deaf Federation of South Africa, told The Associated Press that the interpreter on stage was a "fake."

The man "was moving his hands around but there was no meaning in what he used his hands for," Druchen added.

South African sign language covers all of the country's 11 official languages, according to the federation. It wasn't immediately clear if the unidentified man was using a different method to communicate.

Nicole Du Toit, an official sign language interpreter who also watched the broadcast, told The Associated Press 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."

Various video clips emerged appearing to show the same man signing at previous ANC events.

But ANC spokesman Jackson Mthembu said the interpreter was nothing to do with the political party.

Later Wednesday the party's communications manager Keith Khoza appeared to contradict this when he confirmed to NBC News that interpreter had translated for party events in the past, but only as an unpaid volunteer.

Khoza said the interpreter was employed by the South African government for the Mandela memorial event.

South Africa's Minister in the Presidency Collins Chabane said the administration was looking into the incident.

"Government has noted concern expressed in some quarters about the alleged incorrect use of sign language in the national memorial service," he told a press briefing.

"Government is looking into this matter but has not been able to conclude this inquiry due to the demanding schedule of organizing events relating to the state funeral.

"Government will report publicly on information it establishes but wishes to assure South Africans that we are clear in defending the rights and dignity of people with disabilities."

NBC News' Chapman Bell and The Associated Press contributed to this report.

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