Dutch lender ING Bank said it faces a criminal investigation by authorities in the Netherlands that could lead to "significant" fines.
It said the probe centred around money laundering and other "corrupt practices", adding it had also received requests for information related to this enquiry from US regulators.
Dutch newspaper Het Financieele Dagblad said the investigation was linked to a Uzbekistan bribery case, but a bank spokeswoman would not confirm this to IBTimesUK.
In its annual report published last week the lender said: "ING Bank is the subject of criminal investigations by Dutch authorities regarding various requirements related to the on-boarding of clients, money laundering, and corrupt practices. ING Group has also received related information requests from US authorities."
The bank said it could not determine how long the investigation will take, but "any resulting fines, penalties and/or other outcome could be significant."
In 2012 ING forfeited $619m (£497m, €574m) to the US Justice Department, after the bank moved more than $2bn through the American banking system from the early 1990s to 2007 on behalf of sanctioned Cuban and Iranian clients.