As they mingled with Saudi Arabia’s business and political elite at the Ritz-Carlton in Riyadh last month, the world’s top financiers were effusive in their praise of Crown Prince Mohammed bin Salman’s vision to modernise the conservative kingdom. But 10 days later, with the hotel turned into a deluxe jail for the hundreds of princes and businessmen rounded up in an extraordinary corruption crackdown, the mood of many of the foreigners considering investing in the world’s top oil exporter has turned from enthusiasm to alarm. “Half my Rolodex is in the Ritz right now. And they want me to invest there now? No way,” said one senior investor.

“The wall of money that was going to deploy into the kingdom is falling apart.” The corruption purge, which has targeted some of Saudi Arabia’s wealthiest and highest-profile businessmen, including Prince Alwaleed bin Talal, the billionaire, has been welcomed by Saudis who view it as a much-needed move to recoup what they believe are ill-gotten gains. But foreign investors have been stunned by the speed and scope of Prince Mohammed’s campaign. It has raised concerns about due process in the kingdom at a time when executives were studying proposals to invest in some of the heir-apparent’s grandiose projects, not least a $500bn city in the desert. “One day we are sleeping at the Ritz-Carlton, excited about a new era,” said one regional investor. “The next day they have turned the hotel into a prison — what sort of message does this send us? We some need stability.”