US authorities are investigating German banking giant Deutsche Bank over alleged money laundering in Russia, people familiar with the matter said Monday.

The investigation centers on billions of dollars' worth of transactions carried out by Deutsche Bank in Russia that New York state regulators believe may have been used to disguise money illegally moved out of Russia, the sources told AFP.

The New York Department of Financial Services (DFS) began the investigation of Deutsche Bank early this summer, sources said.

According to these sources, Russian clients unsuccessfully attempted to bribe a Deutsche Bank employee in Moscow in a bid to hide the origin of their money.

A Deutsche Bank spokeswoman said that Germany's largest lender had placed on leave "a small number of individuals" in its Moscow office pending an internal review.

"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," she said.

Deutsche Bank has informed regulators at Britain's Financial Conduct Authority and Germany's BaFin of its internal probe into the Russian division's transactions from 2011-2015.

New York investigators suspect securities bought in Moscow through Deutsche Bank were done in parallel with other Deutsche Bank trades in London in international currencies.

The probe centers on whether these transactions, called "mirror trades," permitted these clients to move large amounts of money out of Russia while hiding the source of the funds, the sources said.

In April, Deutsche Bank was fined $600 million by the DFS, part of fines totaling $2.5 billion by US and British authorities for rigging Libor interest rates, used to peg millions of contracts around the world, in a multi-bank conspiracy.