Some of Singapore’s largest local and international banks are becoming involved in one of the city-state’s largest money laundering cases, involving more than SGD1 billion (USD740 million) in assets.

According to charge sheets obtained by Bloomberg News, some of the individuals arrested and charged this month had funds totaling millions of dollars from unlicensed moneylending in China and illegal gambling at United Overseas Bank Ltd., Citigroup Inc., and RHB Bank Bhd. The charge sheets also allege that they attempted to defraud banks Oversea-Chinese Banking Corp., Standard Chartered Plc., and CIMB Bank Bhd. by using forged documents.

The banks join the city’s real estate agents, precious metals dealers, and golf clubs in being implicated in this scandal. This has raised concerns about safeguards against illicit money entering one of the world’s most important financial centres.

According to the charge sheets, the accused used their criminal proceeds to purchase luxury cars, Tether stablecoins, and, in one case, an upscale condominium unit near the city’s prime shopping belt for SGD23 million. Some allegedly had millions in safe deposit boxes with Certis Cisco Security Pte., a security firm backed by Temasek Holdings Pte., a state investor.

On Wednesday, the majority of the ten people arrested were charged with additional offences in court. Authorities have previously stated that they are seeking documents from at least ten financial institutions in connection with the case, though they have not named them.

Prior to this case, Singapore had been rocked by scandals involving large sums of money from Malaysia’s state fund 1MDB and the German firm Wirecard AG. Financiers have been barred, people have been imprisoned, and banks have been fined for lax controls. In May, lawmakers passed legislation allowing banks to share information on potentially risky customers.