The Singapore police are waiting for documents from at least nine financial institutions in their probe into one of the biggest money laundering cases in the country.

Investigations are still at an early stage, according to public prosecutors at a court hearing on Wednesday. They argued for extending the remand of those arrested and said luxury cars and properties have been seized.

The number of firms in Singapore being questioned highlights growing scrutiny on the extent to which the financial system was used for illicit activities in this case. Authorities last week confiscated more than S$1 billion ($737 million) of properties, luxury cars, cash and other assets, and charged 10 foreigners for allegedly laundering the proceeds of crime from activities such as scams and online gambling.

More than 100 properties, including seven detached houses at the city-state’s luxurious oceanfront Sentosa Cove, 79 condominium units and 19 commercial or industrial spaces, have been banned from disposal by the police.

The police didn’t immediately respond to a request for additional comment. The Monetary Authority of Singapore referred Bloomberg News to an earlier statement last week where it said it takes this case seriously and has been in touch with firms where potentially tainted funds have been identified. The regulator also said it will take firm action against firms if there are breaches of anti-money laundering rules.

So far, charge documents have shown that Citigroup Inc.’s local subsidiary and CIMB Group Holdings Bhd. were allegedly used by some of those arrested in 2020 and 2021. Deutsche Bank AG is also a creditor to a Singapore investment holding company whose two directors were among those arrested.