Sudan's security service on Saturday ordered the closure of a community forum, one of the independently run TEDx events held around the world, even though it was non-political, the organiser said.
"They unplugged the electricity," Anwar Dafa-Alla, who founded Sudan's version of TEDx two years ago, told AFP.
He said almost 1,000 people were attending the event at a luxury Khartoum hotel when officials stopped it before it was even half finished.
"We were only focused on the positive," he said. "We don't do politics."
According to the TEDx website, all TEDx events are organised independently on a community basis but have certain common features, including "lack of any commercial, religious or political agenda".
The New York-based TED is a non-profit agency "devoted to ideas worth spreading," the website says. TED holds two major conferences a year and offers the $1-million TED prize.
Sudanese rights and cultural groups said earlier this year they were under attack after some non-governmental organisations were ordered to close.
The state minister of information and culture, Mustafa Tirab, told AFP in an interview on Thursday that the government "will do our level best to provide freedom of expression and freedom of speech for all those who are inside Sudan".