Deutsche Bank
People walk past a Deutsche Bank logo ahead the banks annual general meeting in Frankfurt May 21, 2015. REUTERS/Kai Pfaffenbach

The United States Department of Justice is investigating trades worth billions of dollars that Germany's Deutsche Bank AG made on behalf of its Russian clients, Bloomberg reported, citing people familiar with the matter.

The probe investigates so-called mirror trades, where the bank's Russian clients bought stocks in rubles, and through simultaneous transactions in London, bought the same stocks in U.S. dollars, thereby moving funds out of Russia without informing authorities, Bloomberg reported.

Last month, The New York State Department of Financial Services (DFS) sought detailed information from Deutsche Bank on possible money-laundering transactions by some of its clients in Russia that could exceed $6 billion in total, a source familiar with the matter told Reuters.

Deutsche Bank declined to comment on this development and referred to its earlier statement published on the issue along with its annual report on July 30.