Billionaire Richard Branson, founder of Virgin Group Ltd., has distanced himself from Saudi Arabia over the disappearance of Washington Post columnist Jamal Khashoggi. (Anthony Kwan/Bloomberg News)

Western business leaders, including Virgin Group founder Richard Branson and tech investor Steve Case, on Thursday distanced themselves from Saudi Arabia over the disappearance and alleged killing of Saudi dissident and Washington Post columnist Jamal Khashoggi.

Their statements are a setback for Saudi Crown Prince Mohammed bin Salman, who has portrayed himself as a reformer intent on modernizing Saudi society and opening it to more foreign investment. The Turkish government has told U.S. officials it has audio and video recordings proving Khashoggi was killed inside the Saudi Consulate in Istanbul this month.

Branson said he was suspending his work as a director of two Saudi tourism projects and suspending discussions with the kingdom’s sovereign wealth fund about a proposed investment in the space companies Virgin Galactic and Virgin Orbit.

“I had high hopes for the current government in the Kingdom of Saudi Arabia and its leader Crown Prince Mohammed bin Salman and it is why I was delighted to accept two directorships in the tourism projects around the Red Sea,” Branson said in a blog post Thursday. “What has reportedly happened in Turkey around the disappearance of journalist Jamal Khashoggi, if proved true, would clearly change the ability of any of us in the West to do business with the Saudi Government. We have asked for more information from the authorities in Saudi and to clarify their position in relation to Mr. Khashoggi.”

Case said he was putting on hold plans to attend a big investment conference in Riyadh later this month, and to participate in a Saudi tourism project.

The website for the Future Investment Initiative conference, taking place Oct. 23-25 in Riyadh, shows dozens of top Western business officials scheduled to attend as speakers. It also lists more than a dozen Western companies as “partners” of the event.

Viacom Inc. chief executive Bob Bakish, who was listed among the speakers, said through a spokesman Thursday he would no longer be attending the conference. Earlier Thursday, Viacom said it was “aware of the reports regarding Jamal Khashoggi” and “monitoring the situation closely.”

Another scheduled speaker, Uber chief executive Dara Khosrowshahi, said in a statement Thursday that he was also withdrawing, and that he was “very troubled” by the reports about Khashoggi. “We are following the situation closely, and unless a substantially different set of facts emerges, I won’t be attending the FII conference in Riyadh,” Khosrowshahi said.

The companies’ announcements follow some by U.S. media organizations and executives, including the New York Times and Los Angeles Times owner Patrick Soon-Shiong, that they would not participate in the Saudi conference.

A spokesman for JPMorgan Chase & Co. said the bank had no comment on whether the Khashoggi case would affect chief executive Jamie Dimon’s plans to speak at the Saudi conference.

Investment firm Kohlberg Kravis Roberts & Co. also declined to comment. Its chairman, Gen. David Petraeus, and co-president, Joseph Bae, are scheduled to speak at the Saudi event.

More than 30 other U.S. and European companies and executives listed as sponsors or speakers for the conference, including MasterCard, McKinsey & Company and Deloitte, did not respond to requests for comment Thursday.

This story is developing.