ChainCatcher reported that Bloomberg quoted people familiar with the matter as saying that Citigroup, DBS Group Holdings Ltd. and several other banks are stepping up scrutiny of their wealthy customers and potential customers to avoid exposure to illegal capital flows after being implicated in Singapore's largest money laundering scandal.

Private bankers at several institutions are also receiving additional training to help them identify tactics criminals use to obscure their backgrounds and the source of their funds, said the people, who asked not to be identified because they are discussing private matters.

The voluntary moves show lenders are working to plug loopholes that allowed a group of criminals to launder more than S$3 billion ($2.23 billion) in online gambling proceeds through at least 16 financial institutions in Singapore. The scandal tarnished Singapore's image and exposed weaknesses in how local and foreign banks and brokerages screened their clients.

The Monetary Authority of Singapore recently completed on-site inspections of some of the banks implicated in the scheme. Banks that had the most dealings with the criminals, including deposit accounts, loans and other financial services, are expected to face fines and other penalties once the financial regulator completes its review, people familiar with the matter said.