1MDB is the scandal that keeps on taking.

Having crippled institutional and political trust in Malaysia, brought down senior figures across the Middle East and triggered intensive investigations from Switzerland to the US, it has now given Singapore's private banking industry its greatest test in a generation.

On Oct 11, the Monetary Authority of Singapore (MAS) threw Falcon Bank out of the country - the second bank to be closed down over 1MDB connections, after BSI in May. It fined DBS $1 million and UBS $1.3 million for breaches of anti-money-laundering requirements and control lapses. Standard Chartered Singapore was fined $5.2 million and Coutts Singapore $2.4 million.

Insiders say that the level of scrutiny private banks in Singapore receive from MAS, already high, is escalating, and that this is far more relevant than the fines.

Mr Rahul Malhotra, the head of South-east Asia and global non-resident Indians at JPMorgan in Singapore, says: "Regulators here want to do the right thing and are way ahead of where I would see the standard globally, in terms of making sure they have the right framework and policies."

But apparently it has not been enough. The Financial Action Task Force, an intergovernmental body, says in a recent report that while Singapore is strong on tackling smaller-scale financial crime, particularly for what it calls "money mules" who courier cash for criminals, it is not strong enough on bigger cross- border cases.

"Singapore should more aggressively target the more complex cases expected of a sophisticated financial centre," it says, noting that few foreign cases were being prosecuted.

So one should expect MAS to get a lot stricter now. That will have consequences. The margins in private banking, already thinning, will get tighter still as compliance and surveillance costs increase, exacerbating a trend for fringe players to exit the business.

And MAS, stung by the misdemeanours on its watch, must show itself to be tough on illegal behaviour while giving the industry enough room to breathe and grow.

The behaviour of Falcon, a Zurich-based lender, does not look good for Singapore. The local branch approved US$3.8 billion (S$5.5 billion) of asset transfers linked to 1MDB between 2012 and last year, under pressure from two board members with links to the Malaysian fund.

It has not escaped the attention of Singaporean bankers that Falcon's Singapore branch manager has been arrested by the Commercial Affairs Department (CAD) and that criminal charges were levelled in October against two former employees of BSI, following an earlier money laundering charge against another former BSI employee in April.

Once the threat of arrest comes into the picture, bankers are very much on notice.

MAS says: "The key underpinning for Singapore's growth as a financial centre over the last four decades has been its high standard of financial regulation and supervision. As an international financial centre, Singapore is exposed to money laundering risks. Having a strong regime for anti-money laundering and countering the financing of terrorism is critical to Singapore's interests."

Falcon and BSI were, as industry insiders put it, "in on it" and deserved to go. But what went wrong at the big guys?

Ms Tan Su Shan, group head of consumer banking and wealth management at DBS Bank says: "While MAS' findings indicate that the bank's control weaknesses are not pervasive, we should have taken more rigorous action with respect to the questionable activity, even if it was intentionally designed to conceal another purpose."

A UBS statement is similar in tone: "We are disappointed we did not do more to detect and report this earlier."

Digging a little deeper, the most common claim is that middle managers did not ask the right questions early enough, and, while all three of the international banks investigated by MAS point out that they themselves alerted the regulator to suspicious transactions, they did not do it quickly enough.

There is a hope that technology will help and in particular, the application of big data as a method of sharing and accessing vital information.

Another challenge for Singapore's private banking industry came with an amnesty on overseas funds from Indonesia. The idea was that Indonesia would forgive the fact that funds had been secreted offshore out of local tax authority reach in exchange for disclosure and a modest tax bill.

To nobody's surprise, most of the overseas assets were sitting in private bank accounts in Singapore. The equivalent of US$50 billion (S$72.4 billion) was declared there and US$6 billion has been repatriated so far.

While this is good news for Indonesia's Budget, it is not ideal for Singapore's private banking industry. The amnesty has raised awkward issues about disclosure and client confidentiality.

In September, it emerged that Singapore's private banks were notifying the police about any Indonesian clients who were declaring under the amnesty.

There is, it seems, a reasonable explanation. Singapore's Suspicious Transaction Reporting Office says banks must notify the office if clients accept the amnesty of another country and none of the Indonesian clients has broken any domestic laws in Singapore by accepting it. The problem is that the filings have to go to the CAD, which is part of the Singapore police authority, making it look like the reporting of a crime.

But unless clients have lied to MAS when sending the funds in the first place, they should have nothing to worry about.

The deputy commissioner of Indonesia's Financial Services Authority, Mr Irwan Lubis, says that OCBC, UOB and DBS have sent reports about Indonesian customers to the Singapore authorities, but that the police will not process them because there is no crime to pursue.

There is a danger in letting these very public matters obscure the bigger picture.

Several bankers say there are far greater challenges to private banking here than 1MDB or the amnesty.

"The bigger challenge is financial disruption, which is already affecting fees," Ms Tan says. "It's a structural issue the industry has to learn to live with. The old, human model is changing and will continue to do so as wealth goes from one generation to the next."

Mr Malhotra at JPMorgan says: "It's no longer a business you can do with sub-scale operations: You need a full-fledged platform with middle office, back office, compliance and legal, the first, second and third line of defence."

EUROMONEY