"Recently, the Dutch central bank determined that we are to review all our retail clients in the Netherlands," Chief Executive Kees van Dijkhuizen said in a statement.

This order followed a record $900 million fine paid by rival  Dutch bank ING in September last year for failing to spot criminal activities financed through its accounts for years.

The company took extra measures to increase customer due diligence at a cost of 114 million euros ($127.75 million) in the second quarter, ABN said, adding that investigations might lead to instructions or fines by the authorities.

Despite the extra expenses, ABN reported a 1% rise in second-quarter net profit to 693 million euros.

Analysts on average had predicted net earnings of 638 million euros in a company-compiled poll, after the lender posted net earnings of 688 million euros a year earlier.