A fake sign language interpreter took to the stage during yesterday’s memorial for anti-apartheid leader Nelson Mandela, gesticulating gibberish before a global audience of millions and outraging deaf people across the world.

DeafSA, South Africa’s leading deaf association, condemned the presence of the unknown man at the memorial to Mandela attended by President Jacob Zuma and scores of world leaders including US president Barack Obama.

While dignitaries were addressing the crowd in the 95,000-seat Soccer City stadium, the young suited man with an official security pass round his neck produced a series of hand signals that experts said meant absolutely nothing.

“He was basically gesturing. He didn’t follow any of the grammatical rules and structure of the language. He just invented his signs as he went along,” said Delphin Hlungwane, an official South African sign language interpreter at DeafSA. “There was zero percent accuracy. He couldn’t even get the basics right. He couldn’t even say thank you.”

Hlungwane said the ‘interpreter’ also failed to impart to television viewers – as he should have done – that the crowd gave a hostile reception to Zuma, a scandal-plagued leader who faces an election in less than six months.

“You’re supposed to indicate with your facial expressions, even if it’s not an exact sign,” she said. “He didn’t indicate that at all. It just passed him by.”

The hunt is on for the mystery man.

“Nobody knows who he is. Even at this hour we still don’t have his name,” Hlungwane said.