Switzerland's financial watchdog said it was in contact with Credit Suisse CSGN.S after media outlets published results of coordinated, Panama Papers-style investigations into a leak of data on thousands of accounts held at the bank in past decades.
One person leaked the information on the accounts, which were held in decades ranging from the 1940s to 2010s, to Germany's Sueddeutsche Zeitung.
The German daily shared it with the Organized Crime and Corruption Reporting Project and 46 other news organisations including the New York Times, Britain's Guardian and France's Le Monde.
Among the allegations were accusations that the bank's clients included human rights abusers and businessmen who had been placed under sanctions.
"We are aware of the articles," a spokesperson for the Swiss Financial Market Supervisory Authority (FINMA) told Reuters.
"Compliance with money laundering regulations has been a focus of our supervisory activities for years now," FINMA added.
Credit Suisse rejected allegations of wrongdoing.
The New York Times said the leaked data covered more than 18,000 accounts collectively holding more than $100 billion.
Shares in Switzerland's second-biggest bank, which had already been under pressure after a series of risk-management scandals and a 1.6 billion Swiss franc loss in 2021, pared initial losses to trade marginally lower in early trading.
"For CS, even if the allegations are unfounded, this raises questions about its business practices in wealth management and should tie up management having to spend time fighting fires instead of moving forward," RBC analysts said.
"Credit Suisse strongly rejects the allegations and insinuations about the bank's purported business practices," Credit Suisse said in a statement issued on Sunday night in response to the consortium's reports.
"The matters presented are predominantly historical ... and the accounts of these matters are based on partial, inaccurate or selective information taken out of context, resulting in tendentious interpretations of the bank's business conduct."
The bank said it had received "numerous inquiries" from the consortium in the past three weeks and reviewed many of the accounts in question.
"Approximately 90% of the reviewed accounts are today closed or were in the process of closure prior to receipt of the press inquiries, of which over 60% were closed before 2015," it said.
"Of the remaining active accounts, we are comfortable that appropriate due diligence, reviews and other control-related steps were taken in line with our current framework. We will continue to analyze the matters and take additional steps if necessary."