"We are committed to participating in international efforts to detect and combat suspicious activities and we take strong action where we find evidence of misconduct," Deutsche Bank said in an emailed statement. "We have placed on leave a small number of individuals from our Moscow operation pending the results of an internal review."
The money laundering could involve $6 billion over four years, people with knowledge of the situation told Bloomberg.
The bank began the investigation after being approached by the Bank of Russia in October and asked to look into the stock trading activities of some clients, Bloomberg said.
Deutsche Bank is looking at trading data from 2011 to early 2015, and is working with the UK Financial Conduct Authority, the European Central Bank and Germany's Federal Financial Supervisory Authority (Bafin), sources told Bloomberg.
The transactions involve stocks bought by Russian clients in rubles through Deutsche Bank, and simultaneous trades through London in which the bank bought the same securities for similar amounts in U.S. dollars, sources told Bloomberg.
Deutsche Bank is currently restructuring after a series of regulatory crises. Co-chief executives Juergen Fitschen and Anshu Jain resigned last week, and it was announced this week that they would be replaced by John Cryan.
In April, Deutsche Bank paid a record US$2.5bn in fines to US and UK authorities over allegations that it manipulated the interbank offered rates (IBOR).
Deutsche Bank said that it would pay £227mn ($340mn) to the UK’s Financial Conduct Authority (FCA) and a combined $2.175bn to the US Department of Justice, Commodity Futures Trading Commission and the New York Department of Financial Services.
The bank was also the target of the United Arab Emirates largest ever fine of AED 30.8mn (US$8.4bn), for "serious contraventions" including misleading the Dubai Financial Services Authority, failures in its internal governance, systems and controls, and failures in its client take-on and money-laundering procedures.
In April, the bank announced cost saving plans designed to save €3.5 billion. The bank plans to reduce its investment bank assets by €200bn, and to focus on key markets and cities as part of its restructuring programme, it said at the time.
Deutsche Bank's Postbank retail arm will also be sold, and $1bn invested in "new digital technologies" across the bank, it said.
The bank also will aim to raise its leverage ratio, measuring capital against assets, to at least 5%, it said.