Saudi Arabia’s stock market tumbled in early Sunday trade on concerns about relations with the international community following the disappearance of the Saudi journalist Jamal Khashoggi.

Khashoggi, a prominent critic of Riyadh and a US resident, vanished on 2 October after visiting the Saudi consulate in Turkey. Ankara believes that he was murdered inside the building and his body removed.

Donald Trump has threatened “severe punishment” if the Saudi government is found to have been involved in the Washington Post columnist’s disappearance. In an interview to be aired on Sunday, the US president told CBS’s 60 Minutes: “We’re going to get to the bottom of it.”

Media companies and some technology executives have pulled out of a Saudi investment conference because of growing outrage over the disappearance and US lawmakers have demanded firm action. Trump, however, has said Washington would be hurting itself if it halted arms sales to Riyadh.

A Gulf finance executive, who declined to be named because of political sensitivities, said: “Concern about the relationship between Saudi and the international community, especially with the US, is causing a big concern for investors.”

Saudi stocks fell 4% in the first hour of trade, with the index touching its lowest since early January, after a 5.8% fall last week sparked by a global sell-off in equities.

Al Rajhi Bank was down 5.3%. Saudi Basic Industries Corporation, the world’s fourth largest chemical firm, was down 4%. National Commercial Bank, the kingdom’s biggest bank by assets, was down 5.5%.

Stocks in the United Arab Emirates rose. Abu Dhabi’s stock index was up 0.2%, largely lifted by property stocks. Eshraq Properties rose 1.6%, and Aldar Properties rose 1.2%.