U.S. Treasury Secretary Steven Mnuchin said he will not attend an international investment conference in Saudi Arabia next week, joining several other high-profile government and business leaders who have withdrawn amid public outcry over the disappearance of journalist Jamal Khashoggi.

Mnuchin announced his withdrawal from The Future Investment Initiative conference in a Twitter post following a meeting with President Donald Trump and Secretary of State Mike Pompeo, who recently met with leaders of Saudi Arabia and Turkey to discuss the Khashoggi case.

Khashoggi, a Washington Post columnist and known critic of the Saudi Arabian government, has been missing since Oct. 2, when he was last seen visiting Riyadh's consulate in Istanbul.

The U.S. has threatened sanctions on Saudi Arabia if the oil-rich nation is found to be connected to Khashoggi's disappearance. Riyadh has warned of retaliation and denied involvement in the incident.

Pompeo, who briefed Trump on his visit to Saudi Arabia and Turkey, said both countries were committed to a full probe into the case and that the U.S. was looking forward to a "complete, thorough investigation in a timely fashion." Pompeo said he advised Trump to give Saudi Arabia "a few more days" to conduct its inquiry, although he did not specify a deadline.

"We have a long, strategic relationship" with Saudi Arabia and "we need to be mindful of that as well" throughout the process, Pompeo told reporters at the White House.

Dubbed "Davos in the desert," The Future Investment Initiative event runs from Oct. 23 to Oct. 25. Business leaders including Uber CEO Dara Khosrowshahi and several media firms have decided not to attend the event.

Other prominent figures who have distanced themselves from the Saudis include Virgin Group's Richard Branson, who suspended proposed investment talks with Saudi Arabia's sovereign wealth fund.