Deutsche Bank CEOs
Co-chief executives of Deutsche Bank Jürgen Fitschen (L) and Anshu Jain announce their resignation last monthReuters

The US Department of Justice is investigating billions of dollars' worth of trades made by Deutsche Bank AG on behalf of its Russian clients this year, Bloomberg reports.

It said the investigation, which has not been reported before, focuses on mirror trades, that allows the bank's Russian clients to move funds out of the country without properly alerting the authorities, a person familiar with the situation told the news agency.

It is believed that Russian clients buy shares in roubles through the bank and then in simultaneous trades through London, the bank purchases the same securities for similar amounts in US dollars, Bloomberg said.

It is believed that in October last year, the Bank of Russia asked Deutsche Bank to look into the trading activities of some of its clients.

Last month, the New York State Department of Financial Services asked for detailed information from Deutsche Bank on some possible money-laundering transactions by some of its clients in Russia that could exceed $6bn (£3.85bn) in total, a source told Reuters.

Bloomberg says the state's Department of Financial Services has asked the bank for e-mails, memos, client lists and other documents.

This will be the third US criminal investigation now pending against the bank. The first involves a probe into whether it rigged the benchmark foreign-exchange rates and violated US sanction laws while the second is with regards to its dealings in mortgage and asset-backed securities.

In April, the bank agreed to a $2.5bn (£1.6bn, €2.2bn) record global settlement with the authorities in both the UK and the US for manipulating the London interbank offered rate and similar benchmarks.

Earlier last month, Bloomberg reported that the bank was undertaking an internal investigation on whether $6bn in trades in Moscow and London were connected with possible money laundering by Russian clients between 2011 and early 2015.

The news agency noted that co-chief executive officers Juergen Fitschen and Anshu Jain both announced on 7 June that they would step down from their roles early. Other than saying the move demonstrated "their attitude of putting the bank's interests ahead of their own," no reasons were given for their departures.

John Cryan took over as sole chief executive following the resignations which came amid protests by investors over recurrent regulatory infringements and poor performance.

On 30 July, the bank confirmed that it was investigating a "significant volume" of suspicious Russian and UK trades and said it has taken disciplinary action against a number of people. It however did not identify the individuals or the amounts involved.

Bloomberg said both Amanda Williams, a Deutsche Bank spokeswoman and Mark Raimondi, a Justice Department spokesman have declined to comment.

Williams referred Bloomberg to the company's interim report on 30 July which said that that bank had advised regulators in several countries, including Germany, Russia, the US and the UK of its investigations.