U.S. Treasury Secretary Steven Mnuchin said Friday that he would still attend a large investment conference in Saudi Arabia this month, in the face of growing evidence that a Saudi journalist was killed inside the Saudi consulate in Istanbul, Turkey.

"I am planning on going at this point," Mnuchin said on CNBC. "If more information comes out and changes, we could look at that, but I am planning on going."

Top Wall Street banks will also attend the high-profile Future Investment Initiative conference in Riyadh, even as a growing list of major media companies and business leaders withdraw from the event and sever business ties with the Middle Eastern country.

British billionaire Richard Branson said Friday that he would end talks over Saudi investment in his Virgin Group's space ventures.

"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," Virgin Group said in a statement.

AOL co-founder Steve Case, Uber CEO Dara Khosrowshahi and Viacom CEO Robert Bakish have said they won't attend the conference in Riyadh.

Media giants such as the The Financial Times, The New York Times and CNN, as well as reporters and editors from The Economist and CNBC, said they would also pull out of the conference, which has depended heavily on journalists to moderate the larger sessions at the annual event.

Journalist 'distressed'

Andrew Ross Sorkin, a CNBC anchor and New York Times business journalist, tweeted he would not attend because he was "terribly distressed by the disappearance of journalist Jamal Khashoggi and reports of his murder."

U.S. Secretary of Energy Ernest Moniz, center, arr FILE - Then-U.S. Secretary of Energy Ernest Moniz, center, arrives at a meeting in Vienna, Austria, July 9, 2015. FILE - Then-U.S. Secretary of Energy Ernest Moniz, center, arrives at a meeting in Vienna, Austria, July 9, 2015.

Former U.S. energy secretary Ernest Moniz said he had suspended his role on the board of Saudi Arabia's planned NEOM business zone until more was known about what happened with the journalist.

The Saudi crown prince said last week that NEOM would build two to three towns each year starting in 2020 and be completed by 2025.

The Harbour Group, a Washington firm that has been advising Saudi Arabia since April, ended its $80,000-a-month contract. "We have terminated the relationship," said a managing director.

World Bank President Jim Yong Kim, who was listed as a speaker, will not attend because of a scheduling conflict, a World Bank official told Reuters on Friday.

HSBC, Europe's largest bank and strategic partner of the event, declined to comment on whether CEO John Flint would still attend.

Tidjane Thiam, the CEO of Credit Suisse, another strategic partner, still plans to attend, according to a source familiar with the matter.

The multinational financial services company Standard Chartered is also planning to attend, a spokeswoman told Reuters.

The CEOs of JPMorgan Chase and Mastercard are scheduled to speak.

Siemens AG, the German manufacturing conglomerate, said there were no changes so far for CEO Joe Kaeser to attend.

News of Khashoggi's disappearance came as the Saudi kingdom was finalizing preparations for the three-day conference that is scheduled to begin Oct. 23.

Last week, Khashoggi went to the Saudi consulate in Turkey to get a document for his upcoming wedding. Khashoggi, a U.S. resident who wrote columns for The Washington Post that were critical of Saudi Arabia, apparently never came out of the consulate.

The newspaper reported Thursday that the Turkish government informed U.S. officials it had video recordings that proved Khashoggi was killed inside the consulate.

Saudi officials have denied any involvement in the reporter's disappearance and said he departed the consulate shortly after entering.